Desmoid tumors (DTs) are a rare and biologically heterogeneous group of locally aggressive fibroblastic neoplasm: their biological behavior spectrum ranges from indolent to aggressive tumors. DTs are classified as intra-abdominal, extra-abdominal, and within the abdominal wall lesions.It is well known that abdominal and extra-abdominal DTs are associated with familial adenomatous polyposis (FAP) and Gardner syndrome. Possible risk factors are prior trauma/surgery, pregnancy, and oral contraceptives.There was a real revolution in the management of DT: from aggressive first-line approach (surgery and radiation therapy) to a more conservative one (systemic treatment and “wait-and-see policy”).In these clinical settings, radiologists play an important role for assessing lesion resectability, evaluating recurrence, monitoring the biological behavior if an expectant management is chosen, and assessing response to systemic treatment as well as to radiation therapy.Awareness of common locations, risk factors, and imaging features is fundamental for a correct diagnosis and an adequate patient management. Illustrate typical locations, risk factors, and histology of DTs.Describe common imaging appearances of DTs.Review the principal differential diagnosis of abdominal DTs.Desmoid tumors (DTs), also called deep/aggressive fibromatosis or desmoid-type fibromatosis, are rare (2/4 new cases per million people) and locally aggressive fibroblastic neoplasm , 2.DTs frequently affect individuals between the ages of 15 and 60 years . The accFurther risk factors are prior trauma/surgery, pregnancy, and oral contraceptives . The horDTs’ biological behavior is strongly heterogeneous: from an indolent behavior with also spontaneous regression  to a very locally aggressive tumor with a high rate of local invasion and recurrence due to the difficulty to achieve negative margins Fig. .Fig. 1PDespite its high recurrence rate , it usually exhibits no distant metastatic potential ; otherwiExtra-abdominal DTsIntra-abdominal DTsAbdominal wall DTsDTs can arise anywhere , so theyThe most common DTs are sporadic and extra-abdominal ones . The typical clinical presentation is a slow-growing painless or minimally symptomatic soft tissue mass.Approximately 30% of patients have tumors related to familial adenomatous polyposis (FAP), and in these patients, intra-abdominal location is the most common type and can be also multifocal .Intra-abdominal DTs’ clinical presentation can be typically as a slow-growing mass but can have also acute presentation such as intestinal ischemia or obstruction .Otherwise, the most common location for pregnancy-associated DTs is the abdominal wall .Knowledge of pathological appearance of DT can help to better understand also the radiological features of DTs and make easier for the radiologists to suggest the diagnosis of DTs , 13.The pathology features are the same in abdominal, intra-abdominal, and extra-abdominal desmoids.Macroscopically, DTs are confined to the musculature and overlying aponeurosis or fascia and rarely (very large lesions) can infiltrate the subcutaneous tissues. They look like scar tissue without a true capsule. This infiltrative aspect is often misdiagnosed by radiologists due to DT well-circumscribed appearance on imaging .Microscopically, DTs are poorly circumscribed and infiltrative. DTs are composed of dense collagenous stroma and long fascicles of band, uniform fibroblasts with low cellularity . PleomorAt the periphery of the tumor, there are entrapped remnants of striated muscle that can go to atrophy that may be mistaken, also by radiologists, for evidence of malignant disease.For all these reasons, the main differential diagnoses are low-grade fibrosarcoma and reactive fibrosis.Immunohistochemistry plays an important role to confirm the diagnosis (such as positivity for smooth-muscle actin and for b1-catenin). Otherwise, nuclear immunoreactivity for b1-catenin is not pathognomonic due to the possibility of false-positive cases  and false-negative cases –17.The histopathologic confirmation is mandatory especially to rule out malignant tumor such as fibrosarcoma. A diagnosis of DT can be performed on core biopsies using 14G or 16G needles at a dedicated diagnostic clinic by a specialist radiologist in conjunction with a sarcoma surgeon. Neither incisional nor excisional biopsy is recommended as the initial diagnostic modality .The biopsy has to be planned in such a way that the biopsy tract can be safely removed at the time of definitive surgery to reduce the risk of seeding .Due to the rarity of DTs, misdiagnosed cases are about 30–40% during initial work-up also in reference centers , 19. PatUS (ultrasound), CT (computed tomography), and MRI (magnetic resonance imaging) have different roles in the diagnosis of DT depending on its locations and clinical presentation.The purpose of this article is to provide a comprehensive review of DT imaging appearance and its pathogenesis Table . We will10% head and neck33% shoulder and upper extremity17% chest wall or back Figs. 30% gluteal region Figs.  and loweThe most common locations of extra-abdominal DTs are as follows –25:10% DTs are multiple in 15% of cases .Clinical presentation of extra-abdominal DT is typically a painless, deep soft tissue mass.Ultrasound examination is the first-line imaging technique to evaluate a palpable mass.DT is visualized as an oval, solid soft tissue mass with smooth or poor margins and variable echogenicity. Due to its heterogeneous composition, it can be characterized by alternate layers of hypo- (matrix and collagen) and hyperechogenicity (cells). Vascularization, evaluated at color Doppler US, can be variable.An example of US features of a gluteal DT is shown in Fig. “Staghorn sign” due to intramuscular finger-like extensions .Some radiological signs that can help radiologist to diagnose a DT are as follows:“Fascial tail sign” (“tail sign”) that corresponds to linear extension along fascial planes . As duraThis represents the local invasion (from the deeper tumor) along fibrous septa into the subcutaneous fat that resembles a branching stag-horn also at imaging .“FasciaDTs show a MR heterogeneous appearance with variable signal on T2-weighted images  and isointense signal on T1-weighted images  The different intralesional components influence the MR signal intensity in the various imaging sequences as shown in Table The so-called band sign is due to heterogeneous, band-like low-signal intensity on both T1- and T2-weighted images. It is considered as a distinguishing feature of DT and corresponds to the dense collagenous stroma. But this sign  is not pathognomonic because it may be visualized also in other benign and malignant soft tissue tumors (such as giant cell tumor of tendon sheath and myxofibrosarcoma).Few studies have reported the features of the DTs on DWI: Oka et al.  found a The higher ADC value of the DTs seems to be due to low cellularity and fibrous content . This inThe contrast enhancement is variable too: 90% of the lesions demonstrate moderate-to-marked enhancement, especially in the more cellular . Non-enhSplit fat sign that corresponds to a thin rim of surrounding fatFlame signs, feathery margins resembling a flame.Extra-abdominal DTs typically have an intermuscular location along the deep fascia, and other important radiological signs at MRI are as follows :Split fAs mentioned before, despite all these typical imaging features, biopsy is still necessary to confirm the imaging impression and to distinguish DTs from other soft tissue tumors Fig. .Fig. 6PAbdominal DTs have a typical higher incidence in female than in male patients, and this data is more evident than in the other locations –34.Otherwise, the relationship between estrogenic stimulus and desmoid formation is not completely understood: some authors described estrogen receptor expression in tumor tissue and clinical efficacy of the antiestrogen therapy. But in many other case series, the lack of female predilection revealed that elevated estrogen levels are not essential for the development of DTs .Also, positive history for previous trauma or surgery is considered as a possible risk factor  .Intra-abdominal DTs’ incidence significantly differs between sporadic and FAP-related cases: only 5% of sporadic DTs are intra-abdominal ones, whereas 80% of cases of FAP-related DTs are intra-abdominal  –38.Abdominal DTs can be divided into pelvic or mesenteric lesions.Mesenteric DT is the most common primary tumor of the mesentery Figs. , and 9.The clinical presentations range from a painless palpable abdominal mass to bowel obstruction or perforation and chronic hydronephrosis due to ureteral infiltration.Mesentery is the most common DT location in the Gardner syndrome .CT is considered as the first level imaging technique for a prompt diagnosis of intra-abdominal DT and their possible acute complications especially in the Emergency Department.CT scans show mesenteric DT often appearing as soft tissue mass with ill-defined margins and radiating spicules extending into the adjacent mesenteric fat , isodense to the muscle. Uncommonly, it can entrap ureters or encase small bowel loops, leading to intestinal perforation or obstruction . OtherwiMR imaging is considered as a second level imaging technique especially for preoperative evaluation of mesenteric masses in selected cases.CT and MR imaging DT features depend on histological and vascular characteristics  is to differentiate DTs (low to mild uptake) from recurrent cancer (moderate to high uptake)  Fig. 8ee8e.Mesenteric DTs have to be distinguished from other mesenteric lesions (primary and metastatic ones).Mesenteric lymphomas typically manifest as a large lesion with well-defined margins, homogeneous attenuation that encases mesenteric vessels (“sandwich sign”), and involve the adjacent small bowel segments Fig.  40].Fi.Fi40].Gastrointestinal stromal tumors (GISTs) can infiltrate the mesentery  or can originate primarily in the mesentery . IntraleMetastatic carcinoid tumor and sclerosing mesenteritis can simulate a primary mesenteric neoplasm at CT scan Fig. .Fig. 12Namely, the primary intestinal carcinoid tumor is often occult at CT  explaining why the mesenteric mass is usually the dominant imaging finding. CT examinations usually show an hypervascular mesenteric mass associated to intralesional calcification (up to 70%) and to an intense fibrotic proliferation and desmoplastic reaction in the mesenteric fat due to the release of serotonin by the primary tumor , the so-In adults, mesenteric soft tissue sarcomas (such as liposarcoma) have to be considered as possible differential diagnosis.Pelvic DTs are considered as a variant of abdominal desmoids due to their location in the iliac fossae and pelvis Fig. .Fig. 13Its typical presentation is asymptomatic slow-growing palpable mass. But larger lesions can infiltrate the urinary bladder, the vagina, or the rectum and can cause hydronephrosis. Moreover, pelvic DTs can compress the iliac vessels and may be clinically mistaken for an adnexal lesion. Although it occurs especially in young women, it is still not considered as a pregnancy-related tumor; otherwise, we propose a case of pelvic DT onset during pregnancy .Abdominal wall DT typically originates from musculo-aponeunotic structures of the abdominal wall and rectus, and internal oblique muscles are the most common site.It is considered as the most frequent pregnancy-related desmoid tumor, and it can occur not only during pregnancy but also during the first year after childbirth . Areas oAs mentioned before, the role of hormonal stimulation is controversial also in pregnancy-related desmoid tumors. Significant estrogen receptor expression has been reported in very few desmoids. Some authors speculate that the “trauma” due to the stretching of the abdominal wall during pregnancy can be the trigger for DTs’ formation. But this hypothesis does not explain why DT (during and after pregnancy) can originate also in other sites and why some DTs have a spontaneous regression after pregnancy. Furthermore, it is reported that some DTs, both in pregnant and non-pregnant patients, respond to antiestrogen treatment .Abdominal wall DTs can be also associated to FAP Fig. .Fig. 14DT development is not only an estrogen-related phenomenon but more complicated, and still unknown hormonal stimulations may be present.Possible differential diagnoses at this location are abdominal wall endometriosis and hematomas of the abdominal wall.US is particularly appropriated for diagnosis and follow-up of pregnancy-associated DT of the abdominal wall due to the lack of ionizing radiation. MRI can be considered as a second level technique in selected cases (DTs show the same features as in the other location) Figs.  and 16.Abdominal wall endometriosis affects young woman and could be associated to deep endometriosis. A positive history of previous surgery is considered one of the possible causes of “seeding” of endometrial cells.At US examination, abdominal endometriosis appears as an oval, hypoechoic solid lesion in the subcutaneous fat, muscle, or fascial layers.At MR, the lesion can be hyperintense on T1-weighted imaging due to the presence of blood products but some lesions may have an intermediate to low signal intensity on T1- and on T2-weighted imaging for a prominent fibrous component .With the aging of population and the widespread use of anticoagulant medications, abdominal wall hematoma  is a common finding especially in older patients. It shows the typical T1 hyperintensity from subacute blood products and contrast enhancement after contrast administration. MRI is often not necessary: correlation to the clinical history is often enough.In the correct clinical scenario, CT examination before and after contrast administration can be used to evaluate active bleeding.The primary role of imaging examination is to define the extension and potential resectability of the lesion.Presently, guidelines recommend observation (“wait-and-see policy” or “expectant management”) as a primary treatment option for unresectable tumors or resectable but asymptomatic tumors .If DTs are managed non-operatively, periodic imaging assessment is mandatory, especially if intra-abdominal . CT is applied to monitor intra-abdominal DTs, and MR imaging is the modality of choice for the follow-up of extra-abdominal and pelvic DTs , 47.MRI is preferred due to the prognostic value of the T2 signal and enhancement Figs.  and 18: Due to the potential risk of recurrence, imaging follow-up has been recommended after therapy, initially every 3–6 months , 47.After chemoradiation, imaging intervals have to be regulated on the basis of the growth rate and presence of symptoms.DTs are uncommon, locally aggressive tumors with a high risk of recurrence. There are several therapeutic options, including “wait-and-see policy,” surgery, radiotherapy, chemotherapy, and hormonal and molecular targeted drugs. A multidisciplinary approach for a “tailored therapy” is usually needed: in this clinical scenario, radiologists play a crucial role to make a correct diagnosis and to guide the proper management, depending on the location, imaging features, and clinical presentation of these kinds of masses.


Myelolipomas are rare benign neoplasms that commonly develop in the adrenal glands. Less frequently, they can affect other organs such as the liver, stomach, liver, lung, and retroperitoneum. It affects more women, with an average age of around 61 years. Histologically, they are composed of mature adipose tissue and hematopoietic cells. With the evolution of immunohistochemistry, there are characteristics that can differentiate from malignant tumors such as liposarcomas. Its treatment remains based on surgical resection and long-term outpatient follow-up. Myelolipomas are uncommon, benign tumors. These are generally solitary and nonfunctioning neoplasms, consisting of mature fat tissue associated with hematopoietic cells that are similar to those found in the bone marrow .In the majority of cases, myelolipomas are located in the adrenal glands. They are rarely found, among other sites, in the retroperitoneum, mediastinum, lung, liver, and stomach .The disease frequently affects the fifth and sixth decade of life . Our casFO, a 64 years old, Caucasian male, follow-up of lower urinary tract symptoms (LUTS) and nonfunctioning kidney due to a chronic ureteropelvic junction obstruction confirmed by DMSA scintigraphy in our service, underwent an abdominal computed tomography (CT) scan in July 2016. In addition to the common abdominal imaging findings, the abdominal CT scan showed an oval image of densified posteromedial fat attenuation in the left kidney .In 2017, the patient underwent prostate transurethral resection for benign prostatic hyperplasia (BPH). He has remained asymptomatic since that time. During an outpatient follow-up in 2019, a new abdominal CT detected a significant increase in mass size, measuring 7.1 x 5.0 x 7.0 cm, without evidence of suspicious lymphadenopathy .The emergence of this abnormality led to retroperitoneal mass resection by laparoscopy transperitoneal approach. The surgical specimen was submitted to histopathology for examination (HP).In the immediate postoperative period, the patient was admitted to the intensive care unit (ICU) for 24 hours in a hemodynamically stable condition without complications. He was then sent to the ward for two more days, where he remained in a satisfactory condition until hospital discharge. The patient currently does not show any signs of tumor recurrence.HP and immunohistochemistry results showed the presence of mature adipose tissue, associated with mixed inflammatory infiltrates and hematopoietic precursors, in addition to amplification of MDM2 and CDK4 gene products, suggestive of myelolipoma Figures  and 4.Myelolipomas are neoplasms of unknown origin, varying in size from 2 to 26 cm. In most cases, myelolipomas are asymptomatic, although larger tumors can cause a mass effect or hemorrhage . Extra-aDiagnosis of these tumors prior to resection, surgery, and/or biopsy is difficult and requires histopathological analysis. In tomographic and/or magnetic resonance imaging, differentiation between myelolipomas and well-differentiated liposarcomas in the retroperitoneum is often not possible . In addiHistologically, myelolipomas can be differentiated from liposarcomas and focal mass-forming extramedullary hematopoiesis. Foci of extramedullary hematopoiesis, e.g., myeloproliferative diseases, hemolytic anemia, and severe skeletal disease exhibit a smaller amount of fat tissue and poorly defined lesions, while myelolipomas are well-defined lesions, composed of varying amounts of mature adipose tissue with cells arising from the bone marrow. Liposarcomas present lipoblasts, zones of cellular atypia, and are less frequently marginalized . ImmunohTreatment still relies on surgical resection. Tumor recurrence is infrequent. With the wider use of immunohistochemistry, these lesions can be more clearly differentiated. However, in settings where access to this resource is unavailable, misdiagnoses may occur. Retroperitoneal malignancies such as liposarcomas can remain undiagnosed, drastically worsening patient prognosis.


Myositis ossificans of the deltoid muscle is extremely rare. We present a case with unique presentation and MRI findings.A 21-year-old female presented with a 3-month history of a swelling in lateral aspect of the right arm. There was no history of trauma, injection, or surgery to the area. Examination showed a 3 × 3 cm firm mass in the deltoid muscle. MRI findings were suggestive of myxoma. Surgical excision was done and histopathology showed the classic features of myositis ossificans. There was no recurrence at the final follow-up 7 months later.Myositis ossificans of the deltoid muscle is very rare with only 6 cases previously reported in the literature. Our case is unique in presentation because it is the first case reported with no history of trauma, Injection, sickness or surgery in the area. We also review the literature for MRI features of Myositis ossificans and show that our case has a unique pattern.We report on a rare case of Myositis ossificans of the deltoid muscle and review of the literature for similar cases and MRI features of Myositis ossificans. We show that our case was unique both in presentation and MRI finding. The first entity is relatively common and presents as peri-articular heterotopic ossification with concurrent severe joint stiffness. This is particularly common at the elbows of burn patients , and at Peri-articular heterotopic ossification of the shoulder may be seen following shoulders surgery . This peWe present a case of myositis ossificans of the deltoid and review the literature on this rare entity. Our case is unique both in presentation and findings on Magnetic Resonance Imaging (MRI). The work has been reported in line with the SCARE criteria .2A 21-year-old female presented with a 3-month history of a swelling in lateral aspect of the right arm. There was no history of trauma, sickness, surgery, or injection to the area. The patient was not married and had no history of pregnancy or vaccinations in the right arm. The swelling has been slowly increasing in size and was only associated with mild pain when she sleeps on her right side. Examination showed a well-defined 3 × 3 cm firm slightly tender mass. The mass was attached to the deltoid muscle. The skin was freely mobile over the mass. The overlying skin showed no erythema A. There 3Our case of myositis ossificans of the deltoid muscle is rare. Furthermore, it is unique both in presentation and in MRI findings.We reviewed all previously reported cases of myositis ossificans presenting as a mass within the deltoid muscle ; and theThe rarity of idiopathic myositis ossificans of muscle may lead to confusion regarding the differential diagnosis. Schultzel et al.  reviewedThe MRI imaging of the various stages of maturation of myositis ossificans is well described in the literature ; and the4We report on a rare case of myositis ossificans of the deltoid muscle and review the literature for similar cases and MRI features of myositis ossificans. We show that our case was unique both in presentation and MRI findings.None.The study was approved by the research committee, National Hospital (Care), Riyadh, Saudi Arabia.Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by Editor-in-chief of this Journal on request.All authors contributed significantly and in agreement with the content of the manuscript. All authors participated in data collection and in writing of the manuscript.Not relevant here.M M Al-Qattan.Not commissioned, externally peer-reviewed.None.


Choledochal cyst (CC) is a morphological malformation characterized by dilatations of the biliary tree that might present later with clinical symptoms, including jaundice, abdominal pain or pancreatitis.Here, we reported a 10-month-old female infant with CC presenting with jaundice and a right upper quadrant mass and who was malnourished following a surgical excision of retroperitoneal teratoma one month ago. Laboratory findings were total bilirubin of 14.17 mg/dL, direct bilirubin of 12.24 mg/dL, gamma glutamyl transferase of 1157 U/L, and alkaline phosphatase 187 U/L. Abdominal computed tomography scan showed a CC that caused dilatation of the proximal common bile duct (CBD), common hepatic duct, and intrahepatic bile duct. We decided to perform an explorative laparotomy and found a CC with diameter of 5 cm. Then, we conducted a Roux-en-Y hepaticojejunostomy. Due to hepaticojejunostomy anastomosis leakage, relaparotomies were done. The patient was uneventfully discharged 17 days after the third surgery.Our findings are unique because the patient had a normal biliary tree previously and underwent intraabdominal tumor surgery. Notably, besides being an acquired CC, our case might be due to inadvertent bile duct ligation during the first operation or bile duct obstruction as a complication of the first operation.CC should be considered as a potential complication of intraabdominal tumor excision, especially if its location is near the CBD. Roux-en-Y hepaticojejunostomy is still the best choice for CC management. •The development of acquired choledcohal cyst (CC) might be due to disruption of the biliary tree especially the common bile duct during the excision of intraabdominal tumor.•Abdominal computed tomography scan is useful and highly accurate to diagnose of CC.•Roux-en-Y hepaticojejunostomy is still the best choice for CC management. Its inc2A 10-month-old female infant was referred to our hospital due to jaundice and right upper quadrant mass. A month before being admitted to our hospital, she underwent surgery in another hospital due to an intraabdominal tumor. Her abdominal computed tomography (CT) scan showed a complex cystic mass located in front of the kidneys and measuring approximately 11.4 × 10.9 × 7.3 cm, and normal common bile duct (CBD) . She hadOne week after the surgical excision, the patient became jaundiced, had pale stool, dark urine and had become malnourished. Due to no improvement after conservative management in the previous hospital, she was referred to our hospital. Her laboratory findings were total bilirubin of 14.17 mg/dL, direct bilirubin of 12.24 mg/dL, gamma glutamyl transferase of 1157 U/L, and alkaline phosphatase 187 U/L. Abdominal CT scan showed a CC that caused dilatation of the proximal CBD, common hepatic duct, and intrahepatic bile duct a.Fig. 2 and the following diagnosis of CC. Interestingly, one previous study reported two cases of mature cystic teratoma at the porta hepatis that were incorrectly pre-operatively diagnosed as CC [We reported a CC case in a child after surgical excision of intraabdominal tumor. To the best of our knowledge, this case is the first report of CC after intraabdominal tumor excision. The development of an acquired CC in our patient might be due to disruption of the biliary tree especially the CBD during the tumor excision. So far, there are no studies about the possible association or any associated syndrome between the first diagnosis of tumor  acquired dilatations resulting from complications of anomalous pancreaticobiliary ductal union; 2) history of previous surgery; and 3) viral infection ,9. MoreoAlthough the second abdominal CT scan was able to show a CC in our case, the magnetic resonance cholangiopancreatography should be performed instead to give more information about the biliary dilatation, the anatomy of the pancreatic duct, the underlined cause of the jaundice, the CC type, and any associated anomalies ,7, whichCC is classified into 4 types: 1) type I, a fusiform/spherical dilatation of the extrahepatic bile duct system; 2) type II, a diverticular dilatation of the extrahepatic biliary tree; 3) type III, a cyst located within the duodenal wall; 4) type IV, multiple cysts within the intra- and the extrahepatic biliary system; and 5) type V (Caroli disease), dilatations of the intrahepatic bile duct .Although she twice underwent re-laparotomies due to anastomosis leakage, our patient was finally discharged uneventfully from the hospital after undergoing Roux-en-Y hepaticojejunostomy. Cyst excision and restoring biliary enteric drainage is the preferred management for CC over internal drainage surgeries because of low morbidity and lower risk of malignant degeneration . The twoThe failure of hepaticojejunostomy anastomosis in our patient might be due to her malnourished condition. There are several factors that can affect the anastomosis healing process, consisting of the primary disease, presence of infection, and patient's nutritional status .4CC should be considered as a potential complication of intraabdominal tumor excision, especially if its location is near the common bile duct. Roux-en-Y hepaticojejunostomy is still the best choice for CC management.The informed consent form was declared that patient data or samples will be used for educational or research purposes. Our institutional review board also do not provide an ethical approval in the form of case report.Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada.The article processing charge of this article was funded by the Gunadi conceived the study. Gunadi and Aditya Rifqi Fauzi drafted the manuscript. Ramadhita, Devy Melati, Elena Sophia Elekta Dilean Siahaan, Eddy Daryanto, Desy Rusmawatiningtyas, and Wahyu Damayanti critically revised the manuscript for important intellectual content. Gunadi, Ramadhita, Aditya Rifqi Fauzi, Devy Melati, Elena Sophia Elekta Dilean Siahaan, Eddy Daryanto, Desy Rusmawatiningtyas, and Wahyu Damayanti facilitated all project-related tasks.The manuscript is a case report, not considered a formal research involving participants.Gunadi.Written informed consent was obtained from the parent of the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.Not commissioned, externally peer reviewed.No potential conflicts of interest were declared.


Tumor-induced osteomalacia (TIO) is a highly unusual disease with enormous difficulties in clinical diagnosis and curative managements. The objective of this study is to report a very rare case who underwent surgical treatment of recurrent spinal phosphaturic mesenchymal tumor. The management of these unique cases has yet to be further elucidated.A 52-year-old man presented with a 3-year history of back pain and 1-year history of continuous and progressive systemic bone pain. The patient, who had been diagnosed of TIO for 3 years, received surgical treatment of extended resection of spinal phosphaturic mesenchymal tumor at L5. Somatostatin receptor tomography revealed the expression of somatostatin in the spine increased significantly, with high suspicion of recurrent phosphaturic mesenchymal tumor.Magnetic resonance imaging of spine and positron emission tomography-computed tomography showed the mass in L5, which was highly indicative of the recurrent pathogenic tumor. Postoperative pathology confirmed the diagnosis of phosphaturic mesenchymal tumor in the spinal region.The patient underwent posterior L5 tumor resection, bone cement reconstruction, L4-S1 spinal canal decompression, and L3-S2 internal fixation.The patient's symptoms improved significantly after the surgery, and we noticed that his hypophosphatemia was successfully corrected after the 2nd operation. Follow-up at 1 month after surgery revealed no recurrence, and the serum phosphorus level of the patient turned to be normal postoperatively. There were no complications associated with the operation during the follow-up period.Taken together, the lesion's clinical features, imaging results, and pathologic characteristics are unique. Combined efforts of specialists from orthopedics, endocrinology, nuclear medicine, radiology, pathology, and medical oncology led to the successful diagnosis and management of this patient. TIO, although rare, should be part of the differential diagnosis when the patient has a history of hypophosphatemia and systemic multiple bone pain. We recommend surgical treatment of the phosphaturic mesenchymal tumor in the spinal region. Osteoplasty by bone cement may be a treatment option for patients with TIO who cannot undergo appropriate surgery or decline open surgery. To date, <500 cases of TIO have been reported in the literature.–3 Therefore, most clinicians have little knowledge of this rare disease and lack clinical experience in diagnosing and treating TIO. This report describes the clinical manifestations, imaging features, diagnosis, and treatment of a recurrent phosphaturic mesenchymal tumor (PMT) of the spine. We also review cases of TIO published in the English literature, and focus on the clinical manifestations and treatment strategies of this rare disorder.Tumor-induced osteomalacia (TIO), also known as oncogenic osteomalacia, is an extremely rare paraneoplastic syndrome characterized by hyperphosphaturia, hypophosphatemia, and elevated alkaline phosphatase levels.2In February 2019, a 52-year-old man presented to our hospital with a 6-month history of increasing systemic multiple bone pain and muscle weakness. In history of present illness, the patient stated he had been experiencing a progressive systemic bone pain and general weakness for 6 months, and continuous and progressive hypophosphatemia for approximately 1 year. The pain in his chest and back can reach 8 to 9 points using visual analog scale (VAS) and cannot be alleviated with rest and hot compresses. It is extremely difficult for the patient to turn over, bend down, and change postures. The patient denied experiencing any other constitutional symptoms and the history of adefovir dipivoxil and any other drugs in the past years. Upon further questioning, he recalled a 3-year history of spinal phosphaturic mesenchymal TIO which was confirmed in our institution in March 2016. Magnetic resonance imaging (MRI) of spine showed the pathogenic tumor was in the left posterior part of the spinal canal at the level of L5, and the dural sac was compressed , tumor markers, and endocrinologic evaluation. The results of the laboratory studies were almost within normal range, except that the hypophosphatemia , reduced alkaline phosphatase , and elevated serum neuron-specific enolase . Osteomalacia was initially diagnosed, with high suspicion of recurrent TIO.The MRI showed the mass at L5, which was highly indicative of the locally recurrent pathogenic tumor Fig. A–H. MRI In brief, posterior complete tumor resection, bone cement reconstruction, spinal canal decompression from L4-S1, and L3-S2 internal fixation were performed according to the original surgical plan. After successful anesthesia, the patient was placed in a prone position for dorsal access to the lumbar spine. For the posterior approach, the paraspinal muscles were detached gently on each side after a midline longitudinal incision was made over the spinous processes. The pedicle entry points were exposed by step-by-step bilateral dissection. At 1st, the previously fixed Sino rods were removed, and the routine screw preparation for bilateral L3 and S2 pedicles were done. The C-arm fluoroscopy showed the location of screw paths is accurate and satisfactory, thus Sino pedicle screws were inserted according to the designed paths. Subsequently, the remaining laminae of L4 and S1 were removed, and scar tissue around the dura mater at L5 level was removed to expose the dural sac and bilateral nerve roots. The suspicious pathogenic tumor tissues were found in the left side of the L5 horizontal spinal canal and the left pedicle of L5, which were completely excised and sent for pathologic examination. During the operation, the examination showed that there was no tension in the dural sac and nerve roots, and the dural sac pulsed with satisfactory decompression. Then the bone cement for reconstruction was prepared, and the bone cement of dough phase was filled in the bone defect after resection of L5 lesions. Then fixation using a screw-rod system was employed. Visual inspection using the intraoperative fluoroscopy showed optimal position of all pedicle screws and bone cement. The incision was closed. Intraoperative blood loss was approximately 900 mL, thus we used no erythrocyte and plasma. Postoperatively, the patient was referred to the regular ward. An X-ray after the surgery confirmed the correct positioning of the implants and bone cement, and no signs of displacement of the screws and rods Fig. A and B. One week after the operation, the VAS score of his systemic pain improved to 1 to 2 points compared to the preoperative status, 8 to 9 points. Serum phosphorus levels significantly elevated to the normal range  plays an important role in the pathophysiologic mechanism of TIO. FGF-23 is highly expressed in pathogenic tumors compared with normal tissue.–3,15–20Notably, one of the most challenging aspects in diagnosing and treating TIO is to find the pathogenic tumor. The feature of PMT delays recognition, diagnosis, and treatment of TIO to some extent. In our case, identifying the tumor and making a final diagnosis took 1 year. According to our review of the literature in PubMed, the average time from the onset of symptoms to the final diagnosis of TIO is usually longer than 2.5 years.–5,21,22 Unfortunately, in most cases, there is difficulty in traditional imaging technology to detect PMT. The classic detection method of TIO is 99mTc octreotide imaging, which is a scanning technology for detecting somatostatin receptor expression.–23 However, because lymphocytes can also express octreotide receptors, nonspecific uptake may lead to false-positive scans of inflammatory tissue, fractures, or other tumors. Similarly, a negative scan of octreotide cannot completely exclude the diagnosis of TIO. This situation emphasizes the necessity of further detection and differential diagnosis of the tumor by PET/CT or whole-body MRI (WB-MRI). However, because of the tumor's size and occult nature in TIO, despite the use of PET/CT, there may be no increase in uptake.–17,23,24 WB-MRI is radiation free and provides excellent contrast resolution for bone, soft tissue, and subcutaneous areas.–24In imaging, TIO shows cortical thickness, osteoporosis, and pathologic fracture.–3,25,26 Due to the complexity of spinal anatomy, PMTs are often difficult to be completely removed. Thus, the partial or subtotal resection might also lead to persistent serum abnormalities remained or tumor recurrence. Rigid internal fixation and effective brace should be insured since osteomalacia may reduce bone resistance and increase the risk of bone nonunion or lead to fracture.–6,25–27 Extent of surgical resection is reported to be correlated with overall survival benefit, and en bloc tumor resection with spinal stabilization is reported to be an option of surgical treatment.–30 However, complete resection may also easily lead to many complications, such as spinal instability, decreased spinal flexibility, neurologic symptoms, neurologic injury, and so on.–30 Osteoplasty by cement augmentation may also be a treatment option for patients with PMTs in the spine, who cannot undergo appropriate surgery or decline open surgery.–30 However, we need to fully recognize the potential risk of complications in bone cement applications. The safety of this approach still needs to be confirmed in further studies with larger sample sizes and longer follow-up periods. One postoperative complication was cement leakage into the canal and subsequent spinal cord compression.–30 The other notable complication is local recurrence after surgery. Under these circumstances, surgical extent, cement volume, and postoperative complications are critical factors that need further investigation.–32 With regard to TIO without accurate location, the combination of vitamin D, phosphorus supplementation, and calcitriol can be used to replace progressive renal phosphorus loss, promote renal production of 1,25-dihydroxy vitamin D, and enhance renal phosphorus reabsorption.–32 However, medical therapy cannot maintain long-term efficacy and potential complications should also be noted, such as hyperparathyroidism, hypercalcemia, and kidney stone formation.,18The ideal treatment for TIO is complete tumor resection of the pathogenic tumor, and this corrects the biochemical abnormalities and remineralizes the bone substance in most cases with TIOs.4The TIO caused by a PMT is rare, and only a few cases in the spinal region have been published. However, this condition may cause serious symptoms and various complications. In summary, this is the 1st reported case of osteomalacia caused by a recurrent PMT in the spinal region. Although osteomalacia caused by a tumor is uncommon, it should be a considered when a patient has a history of hypophosphatemia and systemic bone pain and weakness in the whole body. We suggest complete resection for treating PMTs. For patients with a spinal PMT who cannot have appropriate surgery or who refuse open surgery, bone cement augmentation may be a proper treatment option. This is a safe and effective procedure for relieving pain of patients with spinal TIO and to help localization of the tumor.4.1Written informed consent was obtained from the patient for publication of this article, a copy of which is available for review from the editors of medicine. Because this article does not involve any human or animal trials, it did not require institutional ethical review and approval.The authors thank our colleagues at the Department of Orthopaedic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College.Conceptualization: Shuzhong Liu, Xi Zhou, An Song, Yipeng Wang, Yong Liu.Funding acquisition: Shuzhong Liu, Yipeng Wang, Yong Liu.Investigation: Shuzhong Liu, Xi Zhou, Yong Liu.Project administration: Shuzhong Liu, Yong Liu.Resources: Shuzhong Liu, Xi Zhou, Zhen Huo, Yong Liu.Supervision: Yipeng Wang, Yong Liu.Writing – original draft: Shuzhong Liu, Xi Zhou, An Song.Writing – review & editing: Shuzhong Liu, Yipeng Wang, Yong Liu.


We performed computed tomography every year and pointed out the development of kidney atrophy and a cystic lesion in relation to prolonged hemodialysis, which may be cause of spontaneous renal hemorrhage. A 60‐year‐old man was admitted to the hospital for sudden onset of severe left abdominal pain without any episode of trauma. He had end‐stage renal disease caused by hypertensive nephrosclerosis and had been undergoing peritoneal dialysis treatment for 7 years. Development of kidney atrophy and a cystic lesion in relation to prolonged hemodialysis had been pointed out Figure . He was The other authors have stated explicitly that there are no conflicts of interest in connection with this article.Written informed consent for publishing this case report was obtained from patient.


The incidence of mammary phyllodes tumor is less than 0.3–0.5% of all breast tumors. Only a few pediatric cases have been reported. Here we report a benign phyllodes tumor that occurred in a 14-year-old girl.A left breast mass with a bleeding cyst of about 9 cm was resected after the tumor had rapidly increased in size over the course of 2 months. Imaging examinations suggested an intracystic tumor. Histopathological examination, however, revealed a benign phyllodes tumor without cytomorphism or mitotic figures. The tumor was accompanied by partial bleeding, which was considered to be the cause of the rapid increase in size of the hemorrhagic cyst. The patient remains under observation, and local recurrence has not occurred as of 3 years after surgery.Due to the rarity of the condition in children and adolescents, an individualized, case-based approach is recommended. PhyllodWe report a benign phyllodes tumor with a hemorrhagic cyst occurring in a 14-year-old girl with a rapidly growing, bleeding cyst. This work was written in accordance with the SCARE criteria .2A 14-year-old girl visited our hospital with a left breast mass. She had periodic menstruation and had no family history of breast disease. She had noticed the mass 6 months earlier, and it had dramatically increased in size beginning 2 months earlier. Bloody nipple discharge had also occurred on the day before her visit. A hard elastic mass 9 cm in diameter with good mobility and no tenderness was palpated directly under the left nipple, and the skin directly above was noticeably thinned. The axillary lymph nodes and supraclavicular lymph nodes were not palpable. Ultrasonography revealed a cystic mass 9 cm in diameter, with a recognizable papillary solid component inside . ComputeThe patient provided written informed consent prior to publication of this case report and the accompanying images.3Phyllodes tumors account for 0.3% to 0.5% of all breast tumors. Although they can occur in patients over a wide age range, phyllodes tumors most commonly occur in patients in their 40 s, and pediatric onset is rare. They are rarely observed in adolescents, and only 20 cases have been reported; occurrence especially under 14 years of age is rare ,7.Phyllodes tumors are often palpated as a hard elastic mobile mass. The clinical features of phyllodes tumors include a rapid increase in size. They share similarities with giant fibroadenoma, which is a more serious disease. In general, it is difficult to differentiate between phyllodes tumor and juvenile (giant) fibroadenoma. Typical phyllodes tumors are circumscribed, oval, and hypoechoic solid masses on ultrasonography . A peripPhyllodes tumor of the breast can be classified as benign, borderline, or malignant based on features such as necrosis, margins (pushing or infiltrative), cellular atypia, stromal overgrowth, and the number of mitoses per high power field . AlthougPathological examination is essential for a definitive diagnosis. Imaging examinations in the present case resulted in a preoperative diagnosis of intracystic tumor, but the diagnosis was changed to benign phyllodes tumor after examination of the excised specimen.The present case reaffirms the importance of performing needle biopsy before surgery, for both differential diagnosis and the selection of an appropriate procedure.Surgical excision is the principal treatment for phyllodes tumor. If the tumor is diagnosed as phyllodes tumor on biopsy, wide surgical excision with a safety margin of 1–2 cm should be performed regardless of histologic subtype . A recenIn the present case, since the preoperative diagnosis was intracystic tumor, excision of the mass was performed. The diagnosis was benign phyllodes tumor, and the resection margin was negative. However, even benign phyllodes tumor has a local recurrence rate of about 20%, so careful follow-up is necessary after surgery. Recurrence can develop more than 2 years after surgery, and the present case will require strict follow-up observation in the future. As of 3 years after the surgery, however, no recurrence has been noted and tolerability has been good.Surgery for benign diseases of the mammary gland requires care taking into consideration both curability and functional preservation. Particularly in girls and young women who may wish to breastfeed an infant in the future, excessive invasive treatment should be avoided in consideration of tolerability and mental well-being, and dissection of the mammary gland and duct should be minimized . Even ifFibroadenoma is the most commonly observed breast tumor in pediatric patients, but phyllodes tumor should be considered as a differential diagnosis if a rapid increase in tumor size is observed, as in the present case.4To ensure optimal treatment, careful decision-making regarding the treatment policy, including strict follow-up observation, is necessary. A case-based, individualized approach is recommended, as there is currently no set protocol.Our study has not received any grant of funding.Our institution does not require ethical approval for a case report that are deidentified and collected retrospectively.Written informed consent was obtained from the patient and her mother for publication of this case report and accompanying images.Kimiyau Yoneyama contributed to operation and writing the manuscript.Asuka Hara contributed to operation.Motohito Nakagawa reviewed the work.The authors declare that there is no conflict of interest regarding the publication of this article.


Urothelial pediatric neoplasms are relatively rare. Papillary urothelial neoplasms of low malignant potential (PUNLMPs) and rhabdomyosarcoma (RMS) are the most common bladder malignancies in the pediatric population. Clinical presentation encompasses macroscopic hematuria or lower urinary tract symptoms (or both) or is detected incidentally at imaging. Tumors arising from the bladder can originate from any of its four histological layers  and are divided into tumors that have an epithelial origin (arising from the urothelium) and those that have a non-epithelial origin . RMS is the most common malignant tumor of the urinary bladder in children younger than 10 years. Deriving from the embryonic mesenchymal cell, the histopathologic subtypes of RMS are embryonal RMS (>90%) and alveolar histology (<10%). Pre-treatment imaging should be carried out by computed tomography (CT) or at present is more likely with magnetic resonance imaging of the pelvis. Chest CT and bone scintigraphy are used to screen for metastases. In selected cases, a positron emission tomography scan may be recommended to evaluate suspicious lesions. The current prognostic classification considers age, histologic subtype, tumor site, size, and extent . Staging is based on pre-operative findings, group is based on intra-operative findings and pathology, and risk stratification is derived from both stage and group data. Pre-operative chemotherapy is the most common first-line intervention for bladder/prostate RMS, before surgery or radiation therapy. Collaborative groups such as the Soft Tissue Sarcoma Committee of the Children’s Oncology Group and the European Pediatric Soft Tissue Sarcoma Study Group endorse this therapy. PUNLMPs are generally solitary, small (1–2 cm), non-invasive lesions that do not metastasize. Therapy is usually limited to a transurethral resection of the bladder tumor. About 35% are recurrent and around 10% of them increase in size if they are not treated. Pediatric bladder neoplasms are relatively rare and—with the exception of rhabdomyosarcoma (RMS)—are associated with favorable benign behavior and outcomes after adequate therapy. The incidence does appear to be increasing, according to some studies such as data analyses between 1973 and 2003 using the Surveillance, Epidemiology and End Results (SEER) database. Papillary urothelial neoplasm of low malignant potential (PUNLMP) and RMS are the most common bladder malignancies in the pediatric population. Males were generally more affected than females with bladder malignancies (by a ratio of 2:1)2.Clinical presentation includes macroscopic hematuria or lower urinary tract symptoms or both  and a palpable suprapubic mass or is detected incidentally at imaging2. Ultrasonography (US) is the most common initial examination: a full bladder during examination is advisable to avoid missing small lesions or making a misinterpretation3. If malignancy is suspected, pelvic computed tomography (CT) or—preferably—magnetic resonance imaging (MRI) is performed for better characterization of the location and extent of disease  and the absence of experience of pediatric pathologists in such situations, urinary cytology is rarely usefuldisease . A tissudisease . Work-up4. Urothelial neoplasms are rare in children. Non-invasive urothelial neoplasms are much more common in children than are invasive urothelial carcinomas5. Other relevant but rarer tumors in the pediatric population will also be discussed in this article.Tumors arising from the bladder can originate from any of its four layers  and are classified as tumors with an epithelial origin  or a non-epithelial origin 1, accounting for 5% of all childhood solid cancers6. Males are more commonly affected than females with bladder malignancies (by a ratio of 2:1)1. We assume that, in boys, genitourinary pelvic RMS originates mainly on the prostate and more rarely on the bladder, but owing to the initial extent of the tumor, RMS appears as a bladder prostate primary tumor in the literature. In females, genitourinary RMS originates mostly on the bladder but can rarely be primary from the vagina or uterus.RMSs are malignant tumors deriving from the embryonic mesenchymal cell, which forms the striated musculature. In the genitourinary tract, RMS could affect the bladder, prostate, paratesticular region, uterus, and vagina. RMS is the third most common extracranial solid tumor of childhood (after Wilms’ tumor and neuroblastoma). Overall, 15 to 20% of all RMSs arise from the genitourinary tract. RMS is also the most common malignant tumor of the urinary bladder in children younger than 10 years6. Age of diagnosis is an important risk factor for genitourinary pelvic RMS: rates of event-free survival (EFS) are 53% for those who are less than 1 year or more than 10 years old and 71% for those who are 1 to 9 years old7. Sporadic tumors are much more frequent , but association with genetic syndromes should be considered 9.Genitourinary pelvic RMSs have a bimodal age distribution; the peak incidence occurs within the first 2 years of life  and another peak occurs during adolescence 10.The histopathologic subtypes of RMS include embryonal RMS (>70–90% of cases), are more common in children younger than 10 years of age, and have a favorable prognosis. The alveolar histology (<10–30% of cases) is more frequent in adolescents and confers a lower chance of cure. Macroscopically, these lesions are typically polypoid and gelatinous when they occur in cavities and multilobulated when they are of the botryoid subtype, as shown inPre-treatment imaging preferably should be carried out by CT or MRI of the pelvis and abdomen for nodal area evaluation. The chest should be evaluated by CT. Bone scintigraphy is useful for screening for osseous metastases. Positron emission tomography CT (PET-CT) scan is progressively being used instead in the evaluation of this neoplasm. Bone marrow biopsies are also needed.10. Pelvic and retroperitoneal nodes at the renal artery or below can be affected. Bladder function can be saved in up to 60% of cases by partial cystectomy: while dome tumors are easily resected, lower or extensive lesions require reimplantation of ureters or bladder augmentation (or both) or a neobladder13.After initial work-up, extirpative surgery is indicated for patients whose tumors are localized and amenable to complete resection with minimal morbidity, which is really uncommon in bladder primary neoplasms: only about 12% are likely to be amenable to complete excision at presentation15.Stratification of the risk of RMS is based on a pre-treatment TNM (tumor–lymph nodes–metastasis) staging system and a post-biopsy and resection clinical grouping system established by the Intergroup Rhabdomyosarcoma Study Group (IRS-G), now contained within the Children’s Oncology Group (COG) Soft Tissue Sarcoma Committee. Through the performance of several multicenter randomized trials, this Committee classified the RMS more accurately by tailoring treatment to optimize cancer outcome and minimize treatment-related effects. The current challenge is the risk stratification of tumors by biological characteristics to provide targeted therapies15.The COG classification is divided into pre-treatment staging and clinical groups . Pre-treQuality of the surgery has a major impact on local disease control and correlates with the prognosis. IRS clinical groups are used for disease classification and prognosis . EuropeaCollaborative groups (COG and EpSSG) offer multimodal treatment—local therapy (radiotherapy or surgery) and chemotherapy—in an attempt to improve outcome whilst finding the correct balance between the intensity of treatment and its possible cost in terms of late effects.If tumor resection is not possible , a diagnostic biopsy is required.Group I: completely resected disease and can be treated with surgery only or by additional post-operative chemotherapy. Chemotherapy based on vincristine, actinomycin, cyclophosphamide (VAC) or ifosfamide, vincristine, actinomycin (IVA) combinations is the most common first-line intervention in COG. The EpSSG protocol advised only for vincristine, actinomycin (VA) regimen to reduce long-term gonadal toxicity of alkylating agents.Group II: resected tumor with microscopic residual disease. Need of further treatment is unclear in this scenario. Nevertheless, as for all RMSs, adjuvant chemotherapy is usually required, and radiation therapy is often applied.Group III: gross residual disease after resection, which is the most common situation. Usually, it presents with an unsatisfactory prognosis, and adjuvant local treatment after chemotherapy is a point of debate and study; EpSSG places more emphasis on surgery, and COG on radiation therapy.16. On the other hand, surgery often requires aggressive resection and reconstruction that relies on bladder substitution and need for catheterization. Furthermore, the implications of radiation after surgery and surgery after radiation are debatable, and both generate important concerns in patients who fail the primary local control modality. These issues will persist until data from multi-institutional groups mature. Brachytherapy is a good alternative to apply radiation therapy on the pelvis and is gaining traction in some parts of the world. As a general principle, a conservative strategy must be preferred with partial cystectomy and radiotherapy, rather than radical cystectomy. As long-term effects with brachytherapy appear to be reduced in comparison with external radiotherapy, this technique must be considered, especially in young patients. Proton therapy may replace brachytherapy if the latter technique is not available.Radiation therapy is frequently needed and commonly employed. In general, this is employed for the following cases: (1) unresectable residual tumor, (2) residual disease following surgery, (3) nodal disease, and (4) alveolar histology. There is considerable debate regarding what the best strategy for local control should be. With the ultimate goal of organ preservation, surgery and radiation therapy offer different risks and benefits. Although radiation often allows for lower initial morbidity and preservation of the affected organ, the long-term effects from radiation remain worrisome, especially in young boys (median age of this disease is 2 years old)17.Group IV: metastatic disease that presents a poor prognosis with an overall survival rate of 20 to 30% and whose management has not improved over time; therefore, experimental approaches are needed for these patients13.Surveillance imaging (for at least 5 years) is recommended for patients. The disease recurs in up to a third of the patients, and 95% of relapses occur within 3 yearsALK-1) orNTRK,ROS1 PDGFR, andNTRK, which are far more common in children and young adults16.Inflammatory myofibroblastic tumors of the bladder (IMTBs) are rare (a quarter of these neoplasms occur in children) and are characterized by a benign and reactive proliferation of myofibroblasts. A review of 42 reported cases of pediatric IMTB showed equal prevalence in males and females. Clinical presentation includes hematuria, dysuria, or abdominal pain, and mean age at presentation is 7.5 years (range of 2 to 15 years). The etiology of IMTB is poorly understood and is attributed to infectious or traumatic causes or a possible clonal lesion mainly involving the anaplastic lymphoma kinase gene  may shrink large IMTBs to a more readily resectable size and configuration or eradicate them altogether. It is hypothesized that NSAIDs interfere with vascular endothelial growth factor (VEGF) signaling via inhibition of cyclooxygenase 2 (Cox-2). Target therapies possibly help to induce regression of neoplastic inflammatory masses via three different mechanisms: (1) suppression of the VEGF angiogenesis stimulation (Cox-2/prostaglandin/VEGF pathway), (2) direct inhibition of the proliferation of activated endothelial cells in which Cox-2 is known to be expressed, and (3) an anticytokine suppression effect on the inflammatory process19. There are other drug options, such as vinblastine and low-dose methotrexate18. The armamentarium of systemic therapies has changed in our study period, and the role of classic chemotherapy should be discussed in light of the availability and efficacy of tyrosine kinase inhibitors for unresectable tumors or in case of predicted mutilating surgery.Complete surgical resection of the lesion is the treatment of choice. In children, no proven recurrent/metastatic IMTB has been reported, but follow-up is warranted as recurrent IMTB was previously reported in adults20. Characteristically, these lesions are a solitary, homogeneously attenuating mass. Excision is curative and carries no risk of recurrence or metastasis.Bladder leiomyomas are rare, accounting for less than 1% of all mesenchymal bladder tumor subtypes, and are exceedingly rare in children. Clinical presentation includes urinary obstruction, frequent urination, dysuria, and hematuriaParaganglioma. The origin of bladder paragangliomas is related to the embryonic rests of chromaffin cells in the sympathetic plexus of detrusor muscle. These tumors are exceedingly rare .22.Bladder paragangliomas are usually benign, but 10% may be malignant . Clinical presentation might be related to catecholamine excess, including hypertension and headache, sometimes related to micturition22.Paragangliomas tend to be vascular tumors with avid enhancement characteristics at MRI. A PET scan may be employed to confirm diagnosis and to identify metastatic lymph nodes. Pre-operative care—including adrenergic blockade—is necessary to avoid an intra-operative hypertensive crisis. Surgical resection is usually curativeNeurofibroma. Up to 75% of bladder neurofibromas are detected in children, and the bladder is the most common genitourinary site for these tumors. Bladder wall spinal and autonomic nerves can be involved. Patients can be completely asymptomatic or present voiding dysfunction. Bladder tumors may be the first manifestation of neurofibromatosis type 1 (NF1), and the cutaneous stigmata of the syndrome is occasionally identified24.24. Differential diagnosis includes RMS and paraganglioma. Debulking resection provides symptom relief, as complete resection is difficult because of the plexiform nature of these neoplasms. Malignant transformation of neurofibromas in a malignant peripheral nerve sheath tumor is rare but should be considered in case of pain or a rapidly growing tumor or both.Neurofibroma usually is depicted as a benign solid mass . Homogeneous low signal intensity on T1-weighted images and high signal intensity on T2-weighted images are the most common patterns at MRI25.The response to chemotherapy or radiotherapy is poor, and the majority of cases of NF1 with bladder dysfunction are managed by surgery. Surgery has inherent complications in these patients. Immunosuppression and chemotherapy increase the risk of infection, the need for extensive resection of these tumors leads to significant lymphedema, and skin invasion or malnutrition exposes these patients to poor healing. Because complete resection of genitourinary plexiform neurofibromas is often difficult, non-continent urinary diversions are the method of choice26.The best long-term outcome following malignant transformation is achieved after complete resection with clear margins. This means that, when malignization appears during follow-up, surgery must be proposed without delay28. Sonographically, vascular tumors may present as a polypoid solid mass with increased vascularity or less commonly as a diffuse bladder wall thickening. Usually, these tumors are solitary and are seen at the bladder dome or the posterolateral bladder walls. Syndromes such as Klippel–Trénaunay–Weber, Sturge–Weber, and Proteus are associated with tumor multiplicity28.In children, vascular tumors are exceedingly rare within the bladder and usually manifest as painless recurrent macroscopic hematuriaAblative treatment is the standard of care; a partial cystectomy may be necessary for large tumors. Sclerotherapy has emerged as an option of bladder hemangioma management following a successful experience with this method in other body sites.28.Lymphatic and arteriovenous malformations and bladder wall telangiectasia (in the setting of ataxia–telangiectasia) are differential diagnosis. Epithelioid hemangioendothelioma and angiosarcoma should be considered in aggressive casesUrothelial neoplasms in children are rare and predominantly non-invasive. Lesions were classified in accordance with the 2004 World Health Organization/International Society of Urological Pathology criteria as urothelial papillomas (UPs), PUNLMPs, and low-grade urothelial carcinomas and high-grade urothelial carcinomas.30.At presentation, the most common symptom is painless hematuria. In the presence of hematuria, US must be performed. If a bladder lesion is identified, transurethral resection of the bladder should be performed. The lesions are usually solitary, non–muscle invasive, and of low grade (mainly UPs and PUNLMPs) . There iPapillary urothelial neoplasm of low malignant potentials. PUNLMPs are common bladder lesions in children and are used to describe a urothelial tumor that resembles exophytic urothelial. They are normally solitary and small (1–2 cm), commonly occur at the posterior lateral walls and ureteric orifices of the bladder, are non-invasive, and do not metastasize. About 35% of PUNLMPs reportedly recur after complete resection, and around 10% of them increase in size if they are not treated; therefore, regular imaging surveillance is advocated30.Urothelial papilloma. UPs are benign polypoid urothelial neoplasms that are infrequently reported in children. Microscopically, a broad vascular core covered by a normal urothelium and no cytologic atypia is the pattern.30.UPs have a frond-like appearance in imaging. Transurethral excision is the treatment of choice. Because UPs seen in adults are known to recur, US follow-up has been advocatedUrothelial carcinoma. Urothelial carcinomas are rare and, in children, have a different clinical course. Most of these tumors are solitary, have a low-grade morphology, are associated with a low risk of recurrence, and seldom involve the upper urinary tract. They are much more common in adolescents; only 30% of cases occur in children who are 10 years old or younger30.30.Urothelial carcinoma may occur in childhood cancer–predisposing syndromes such as Costello syndrome and hereditary non-polyposis colorectal cancer syndrome. Augmented bladders have an increased risk of developing urothelial carcinoma, usually at bladder-intestinal anastomosis, and these tumors are frequently of high grade and have a more aggressive behavior31.No criteria have been established for treatment and follow-up for these children with urothelial carcinomas. For most patients, treatment is transurethral resection of the bladder tumor (TURBT). There is no recommendation of adjuvant therapy following resection as these tumors are rare in a pediatric age group. Some authors have performed partial cystectomy instead of TURBT in view of the risk of perforation of the pediatric bladder. Some reports also have given treatment with mitomycin C along with TURBT. There is no standard surveillance protocol for the imaging follow-up of patients who have received treatment, and recurrences have been reported, especially in cases with multiple tumors32.Nephrogenic adenoma (NA) of the urinary bladder is a metaplastic change in the urinary bladder and has papillary or cryptic structures similar to those seen in renal tubules. Microscopically, NA consists of small to medium tubules, cysts, or papillae coated by cuboid epithelium to low columnar epithelium with eosinophilic cytoplasm. Genitourinary trauma and chronic inflammation are factors that predispose patients to exfoliation of renal tubular cells, leading to sowing in the urinary tract, especially to the urinary bladder. Several patterns of growth  have been reported in isolation or combined (mixed morphology)32.NAs, in contrast to other bladder tumors, commonly manifest with frequent urination rather than hematuria. For treatment, removal of the causative factors and excision of the lesion are required26. It is therefore questionable that prophylactic resection of incidental urachal remnants plays a role in preventing future malignancies33.Urachal anomalies are thought to be associated with an increased risk of bladder adenocarcinoma in adults. Urachal anomalies are found incidentally in about 1% of children, and most anomalies are asymptomatic urachal remnants. The incidence of urachal malignancy in adults is extremely low , and there is only one case described of urachal adenocarcinoma in children


The authors report one case of schwannoma located in the sciatic nerve, just above the popliteal fossa. A sciatic localization is rare, observed in 1% of the patients. The misleading clinical presentation of this localization causes a delay in diagnosis. Magnetic Resonance Imaging (MRI) is the imaging modality of choice, but the final diagnosis is made by the histological examination of the tumor. Schwannoma should be surgically removed without division of the nerve trunk. Schwannoma is a benign tumor generally observed on peripheral nerves especially in the upper limbs . It is oSince the identification of this tumor by Verocay in 1908, several names are used  making terminology confusing, but the two most common terms utilized today is schwannoma and neurilemoma . In the The most common manifestation of schwanomma is pain, sensory and motor dysfunction, mimicking sciatica. A painless mass can be palpated with a positive Tinel’s sign.It often has a long subclinical course and their clinical presentation is usually misleading.This clinical case describes a schwannoma of the sciatic nerve mimicking sciatica.A 50-year-old-woman presented painful path involving the left lower limb with a painful mass just above the popliteal fossa.The initial symptoms started some months previously.Physical examination revealed a mobile mass just above the left popliteal fossa. The mobility of the knee was normal. There was no neurologic or vascular deficit.Ultrasound revealed a well-defined mass with contact to the sciatic nerve in the distal posterior part of the left thigh .Magnetic Resonance Imaging (MRI) revealed a well-defined heterogeneous mass , posterior to the sciatic nerve, just above the popliteal fossa . A T2-weBiopsy under ultrasound scan was made. Histological examination revealed a schwannoma.February 12, 2010, the resection of the tumor was performed according to microsurgical principles.The patient was placed in a prone position. A longitudinal incision was made over the left popliteal fossa. A well-delineated tumor was identified, originating from the sciatic nerve proximal to its bifurcation . The tumHistological analysis of the tumor showed a nodule with a capsule with high and low cellular regions called Antoni A and B areas, respectively, and a blood vessel with a hyalinized wall .Postoperatively, the patient did not develop pain and motor or sensitive disturbances after a follow-up of 16 months; ultrasound scan was normal.Schwannoma is rare but it is the most common benign nerve sheath tumors, especially in the upper limbs .A sciatic localization is rare and it is often located in the posterior tibial nerve , 7.Most schwannomas are solitary lesions. Malignant transformation occurs rarely –5, 11.A schwannoma may often present as a painless, palpable mass with a positive Tinel’s sign , 8, 12. In our case report, the clinical presentation was easier because the patient presented painful path involving the left lower limb with a painful mass.The nerve conduction study and standard radiography are not contributory.The ultrasound examination may show the mass, but the contacts with the nerve are not easy to study . MRI ideThe final diagnosis is possible by histological analysis .Enzinger and Weis described the several microscopic feature characteristic of a schwannoma, found in our case. They are: (1) high and low cellular regions called Antoni A and B areas, respectively; 2) in the Antoni A area, there may be foci of palisaded nuclei called Verocay bodies; 3) relatively thick capsule [ in the A relativeSurgical treatment is the treatment of choice , 16, 17.In the literature, the incidence of recurrence is low  and it mIn conclusion, the persistence of sciatica despite a negative routine workup should indicate the possibility of peripheral nerve neoplasms. MRI is the radiological examination of choice, but the final diagnosis is made by the histological examination of the tumor.The treatment of choice of schwannoma remains the surgical resection without division of the nerve trunk.The incidence of recurrence is low and may due to an incomplete resection.The authors declare that they have no conflict of interest.


Spitz nevus is a benign melanocytic lesion, which presents in several ways: solitary, agminated, or disseminated. The disseminated variant is uncommon; it may have a rapid evolution (the eruptive form) and be difficult to manage. This report presents the case of a 24-year-old patient with multiple papules on his limbs, which had appeared four years previously. On physical examination, 120 pink and skin-colored papules were seen, which under dermoscopy were observed to be homogeneous, pink vascular lesions. Histopathologic study revealed epithelioid cells arranged in groups or singly in the dermis and dermo-epidermal junction. They were HMB-45 positive in the superficial dermis, and Ki-67 < 1%. Given these findings, a diagnosis of eruptive disseminated Spitz nevi was made. Spitz nevus is a benign melanocytic lesion, which presents in a wide variety of clinical and histopathologic expressions. Its biological behavior over time tends to be uncertain. It is classified into solitary, agminated, and disseminated forms. Disseminated Spitz nevi is a rare presentation that may have a rapid (eruptive) evolution, or may develop over a prolonged period of time, several years (non-eruptive).2This report presents the case of a Chilean patient with eruptive Spitz nevi, given the unusual nature of this clinical variant and the few reports in the literature.A 24-year-old male patient, with no significant morbid history. He was referred to this hospital because of the appearance, four years previously, of multiple raised lesions on the arms, elbows, thighs, and knees. They had a rapid progressive evolution in size and number, with no mention of pain, pruritus, hemorrhage, or other problems. Some lesions, mainly on the arms, had spontaneously resolved after ten to 12 months. On physical examination approximately 120 pink and skin-colored papules were seen, with a warty appearance and a sessile base. Some were pedunculated. They were from 2 to 9 mm in diameter, and were symmetrically distributed on the knees, thighs, elbows, and arms . DermoscEruptive disseminated Spitz nevi was described in 1974 as juvenile eruptive melanoma, by Wallace et al.In adults, a solitary Spitz nevus is usually treated by surgical removal, after clinical diagnosis, given its uncertain biological behavior. In practice, this is difficult to do in the eruptive variant, considering the number of lesions seen. Various therapeutic options have been tried, such as electrocoagulation,Pablo Vargas: Approval of the final version of the manuscript; conception and planning of the study; elaboration and writing of the manuscript; obtaining, analyzing, and interpreting the data; effective participation in research orientation; critical review of the literature; critical review of the manuscript.Rodrigo Cárdenas: Approval of the final version of the manuscript; obtaining, analyzing, and interpreting the data; critical review of the literature; critical review of the manuscript.Roberto Cullen: Approval of the final version of the manuscript; obtaining, analyzing, and interpreting the data; critical review of the literature.Andrés Figueroa: Approval of the final version of the manuscript; obtaining, analyzing, and interpreting the data; intellectual participation in propaedeutic and/or therapeutic conduct of the cases studied; critical review of the manuscript.None declared.None declared.


Main Teaching Point: Multiple osteolytic calvarial lesions in a child raise suspicion of Langerhans cell histiocytosis. A four-year-old patient presented to the otorhinolaryngology department with left-sided otalgia and otorrhagia. On clinical examination, the left external auditory canal appeared edematous and hemorrhagic. Computed tomography (CT) of the temporal bone was performed, which demonstrated an osteolytic process in the left anterolateral mastoid Figure . AdditioLangerhans cell histiocytosis (LCH) is a rare hematologic disorder, characterized by proliferation of antigen-presenting dendritic cells called Langerhans cells. Incidence is estimated at 2–20 per million, with a slight male predilection and a peak between one and three years of age. Depending on the number of lesions and systems involved, the disease is composed of three categories. Eosinophilic granuloma is limited to one or a few bones with potential lung involvement. Hand-Schüller-Christian disease involves multiple bones, the reticuloendothelial system and the pituitary gland. Letterer-Siwe disease is disseminated disease with fulminant clinical course. Osseous lesions are the most common manifestation of LCH, most often in flat bones such as the skull, mandible, ribs, pelvis, and spine. On imaging, bone lesions appear as osteolytic defects (“punched-out lesions”). On radiographs, calvarial lesions often demonstrate a double contour caused by asymmetrical involvement of the inner and outer tables, called the “hole within a hole” or “bevelled edge”-sign. MRI is superior in the evaluation of an associated soft-tissue mass or dural invasion. On MRI, osseous lesions most often demonstrate intermediate T1 and increased T2 signal intensity and avid contrast enhancement, as was the case in our patient. Involvement of the hypothalamic-pituitary axis is characterized by an absence of high signal intensity of the posterior pituitary on T1-weigthed imaging and a thickening and enhancement of the pituitary stalk. Both findings were also present in our case. In the absence of organ dysfunction, prognosis of children with either localized or multifocal LCH is excellent [


Postoperative complications after brain tumor surgery occur occasionally and it is important for clinicians to know how to properly manage each complication. Here, we described a rare case of late-onset, subdural fluid collection localized at the resection cavity that caused motor weakness after convexity meningioma resection, requiring differentiation from an abscess, to help clinicians determine treatment strategies. A 58-year-old right-handed female was admitted to the hospital with a headache and posterior neck pain. Brain computed tomography (CT) scans and magnetic resonance (MR) images showed a homogeneously enhanced, calcified, and multi-lobulated mass adjacent to the right motor strip without perilesional edema. The patient underwent surgery without incident or residual deficit and was discharged from the hospital in good condition. Six weeks after surgery, the patient complained of left arm monoparesis without infection-related symptoms. Brain imaging studies showed a localized fluid collection in the resection cavity with an enhanced margin and perilesional edema. Diffusion restriction was not detected. After three months of conservative treatment without surgery or antibiotics, she recovered from the neurologic deficits, and brain imaging studies showed the spontaneous regression of the fluid collection and perilesional edema. Late-onset, localized fluid collection at the resection cavity, which is similar to an abscess, could occur three to eight weeks after meningioma resection. When there are predisposing factors, including blood components and hemostatic materials in the surgical cavity, it is important for clinicians to understand this type of complication and choose conservative management as a feasible strategy. After craniotomy for brain tumor removal, postoperative complications occasionally occur. For appropriate management, the clinician should be well-aware of the types, differential diagnosis, treatment strategies, and course of the complications . It is eA 58-year-old right-handed female presented to the clinic with a headache of long duration and a two-week history of posterior neck pain. She had no significant medical or family history. No other neurological deficits were noted. Brain computed tomography (CT) scans and magnetic resonance (MR) images demonstrated a homogeneously enhanced, calcified, and multi-lobulated mass adjacent to the right motor strip without peritumoral edema A–C. The Six weeks after surgery, the patient complained of sudden left arm monoparesis. The CT scans and MR images revealed localized subdural fluid collection at the resection cavity with enhanced resection margin and perilesional edema, showing an iso-signal intensity of the cerebrospinal fluid (CSF) on T2-weighted and T1-weighted images. Diffusion restriction was not noticed A–C. TherComplications after craniotomy surgery are not rare and are well-known to clinicians. The resection of convexity meningioma can induce several well-known site-specific complications, including abscesses, hemorrhages, or venous infarctions . We presThe underlying mechanisms of this complication are suspected to include many causative factors. Like subdural hygromas and tumor bed cysts, arachnoid tears and flap valves might be triggering factors. Sufficient dura-arachnoid interspace after the removal of a convexity meningioma might contribute to subdural fluid collection ,4. SubduAfter meningioma surgery, the surgical site shows a well-enhanced, thickened meningeal membrane by three to eight weeks after surgery, which usually resolves after six months or more. Usually, well-enhanced granulation tissue is replaced by less-enhanced collagen. Furthermore, when there are blood components in the subdural fluid, persistent membrane enhancement is more prominent. This strong enhancement of the meninges after surgery is due to reactive granulomatous inflammation limited to the surgical site . ReactivIt is difficult to distinguish imaging features of persistent subdural fluid collection due to granulomatous inflammation, subdural empyema, or tumor recurrence. Brain MR imaging techniques, including T1- or T2-weighted, fluid-attenuated inversion recovery (FLAIR), and diffusion weighted images (DWIs), are helpful in distinguishing empyema or tumor recurrence, but this is not always the case . Brain iBecause of deficient examples in the pertinent literature, definitive treatment strategies for this complication are not decided yet. Symptomatic necrotizing lesions caused by granulomatous inflammation can be treated with surgical intervention to exclude brain abscesses . As showIn conclusion, late-onset subdural fluid collection localized in the resection cavity, similar to an abscess, can occur after convexity meningioma surgery. Blood components and exogenous materials in the resection cavity may exacerbate CSF accumulation and induce neurologic symptoms. Even though neurologic symptoms are triggered by this complication, it is important for clinicians to choose conservative management as an initial treatment strategy.


All 3 hedgehogs with eosinophilic leukemia were older than 2 years of age; in contrast, 4 of 6 cases of acute leukemia/lymphoma were <2 years old. Hedgehogs presented for non-specific clinical signs of anorexia and lethargy. On hematologic testing, hedgehogs with eosinophilic leukemia had a marked leukocytosis, consisting mostly of eosinophilic precursors with fewer mature eosinophils, whereas there were 43–97% immature cells (blasts) in the blood of hedgehogs with acute leukemia/lymphoma. Anemia (n = 6) and/or thrombocytopenia (n = 6) were concurrent findings. Increased liver enzyme activities  and hypoalbuminemia were the common findings on biochemical panels. All cases of eosinophilic leukemia and 4 cases of acute leukemia/lymphoma died shortly after diagnosis , whereas 2 cases of acute leukemia/lymphoma lived for 94 or 101 days. Postmortem examination in 5 cases  showed bone marrow infiltrates, confirming eosinophilic leukemia and acute leukemia in 1 and 3 cases, and bone marrow necrosis in 1 animal with acute leukemia/lymphoma. Immunohistochemical staining of bone marrow sections confirmed a T-cell acute leukemia in 1 case. Several hedgehogs had concurrent carcinomas. Hedgehogs suffer from eosinophilic leukemia and acute leukemia/lymphoma. However, classification of acute leukemia by lineage was not possible due to lack of hedgehog cross-reactive or species-specific reagents.Previous reports of leukemia in hedgehogs are limited. We describe clinicopathologic features of leukemia in 9 hedgehogs, including eosinophilic leukemia ( Spontaneous neoplasia is common in African Pygmy hedgehogs, with a reported disease prevalence of 30–60% –6. The mLeukemia is defined as a hematopoietic neoplasm involving the blood and/or bone marrow. Leukemia can be further classified as acute or chronic, based on the degree of cellular differentiation, and as myeloid, lymphoid, or mixed lineage, based on the cell lineage. Acute leukemias which lack detectable differentiation markers are classified as acute undifferentiated leukemia . With lyn = 2), lethargy (n = 2) and collapse (n = 1). Physical and imaging findings were variable, with one animal having an osteolytic gingival mass and a second animal having hepatosplenomegaly (n = 3), hyperbilirubinemia (n = 2), hypoalbuminemia with hyperglobulinemia (n = 2), and hypercalcemia (n = 1). Bone marrow aspirates were not performed in any case. Cytochemical staining for myeloperoxidase (MPO) , ALP (Sigma-Aldrich. procedure No. 85), α-naphthyl-butyrate esterase (ANBE) , chloroacetate esterase (CAE) , and Sudan Black B (SBB)  was performed on blood smears from case 2 and a control hedgehog with normal hemogram results. Luna staining was also done on smears from case 2 and another hedgehog with normal hemogram results. Eosinophils were positive for MPO, ALP, SBB, and Luna stain in blood smears from the control and leukemic hedgehogs. Mature eosinophils in the control and leukemic hedgehogs were negative for ANBE, but a few immature eosinophils in case 2 with eosinophilic leukemia were positive for this stain. Mature and immature eosinophils in case 2 with eosinophilic leukemia were negative for CAE, contrasting with mature eosinophils in the control hedgehog, which were positive for CAE. Neutrophils in the control and leukemic hedgehogs were also positive for CAE, serving as an internal positive control. The different staining patterns for ANBE and CAE in eosinophils of case 2 with eosinophilic leukemia were considered aberrant. The presumptive blasts were negative for all stains. Follow-up information was available on 2 hedgehogs. Case 1 died on the day of admission, whereas case 3 was treated with prednisolone  but died 41 days later (Three hedgehogs were diagnosed with eosinophilic leukemia (cases 1 to 3). Animals were between 2 and 4 years of age and a mix of sexes . They wenomegaly . A hemognomegaly . Eosinopnomegaly . All affnomegaly . Moderatys later . A postmys later  and theiys later . Neoplasn = 2), mesenteric lymphadenopathy (n = 1), masses in the cervical region (n = 2), uterus (n = 2) and ovary , gingivitis (n = 2) and a gastric foreign body (n = 1) (n = 4) and ALP (n = 5) activities (Six hedgehogs were diagnosed with acute leukemia/lymphoma (cases 4 to 9). Their median age was 1.7 years (range 1.3–3 years) and all were intact females. Clinical signs were variable and non-specific . Physica (n = 1) . All 6 c (n = 1) . The rem (n = 1) . All anitivities . One anitivities . Bone mativities . No hemativities . These ftivities . A diagntivities  with no tivities . The fintivities , but inftivities , which htivities . Biochemtivities . An aspiThere are limited reports of leukemia in pet African hedgehogs and most previously reported cases were diagnosed at postmortem examination, with little description of clinical pathologic findings –16. HereThe hedgehogs presented with non-specific clinical signs and were mostly intact female  and middle-aged to older animals. Hemogram results were indicative of a leukemia, revealing a marked leukocytosis, consisting mostly of immature eosinophils in animals with eosinophilic leukemia or a high proportion of blasts in animals with acute leukemia/lymphoma. Most animals had concurrent cytopenias, predominantly a non-regenerative anemia and/or thrombocytopenia, which could be due to marrow infiltrates , bone marrow necrosis , an abnormal marrow microenvironment and concurrent peripheral causes . Biochemical results revealed liver injury and hypoalbuminemia in most animals. The liver injury was attributed to tumor infiltrates and/or hypoxic injury whereas the hypoalbuminemia may be due to a negative acute phase response, anorexia or protein loss.Three of the 9 cases were diagnosed as eosinophilic leukemia, based on a marked eosinophilia consisting mostly of immature cells, showing eosinophilic differentiation. Based on the lack of blasts in blood, the leukemia appeared chronic vs. acute, however bone marrow aspirates were not performed in all animals to assess the percentage of blasts. In veterinary medicine, chronic eosinophilic leukemia is a rare hematopoietic neoplasm with an indolent course that has been reported in cats , 19. GivFour cases were diagnosed with acute leukemia based on the presence of many blasts in blood and substantial bone marrow involvement in aspirates or postmortem tissue sections without clinical, imaging or histopathologic evidence of major organomegaly or extramedullary masses. One of these cases had diffuse marrow necrosis, presumably from death of the tumor cells in marrow, since postmortem examination showed a leukemic pattern of distribution in extramedullary tissues with no obvious masses. Spontaneous bone marrow necrosis has been rarely described in acute leukemia in humans  and animSix animals in this report were given prednisolone at 1–2 mg/kg SID, including 1 with eosinophilic leukemia and 5 with acute leukemia/lymphoma. However, the treatment was of unclear efficacy as most animals died within a month of diagnosis. The cause of death was unclear and could have been due to the leukemia or concurrent neoplasms, which were evident in 2 of the animals on postmortem examination. Our results are similar to that of other reports, where prednisone and cytarabine treatment of eosinophilic leukemia resulted in a limited response , 16. GivA limitation of this study is that the leukemia could not be phenotyped in most cases, except for the eosinophilic leukemia, where cell lineage was discernible by morphologic features alone. There are limited reagents for immunophenotyping leukemia in exotic pets or animals, such as the hedgehogs in this case series. We used antibodies against CD3 (T cell marker), CD20 (B cell marker), and Iba-1 (macrophage marker), however a positive reaction was only obtained for CD3 in one case. Cytochemical staining was done on one case of eosinophilic leukemia, along with a hedgehog control, and revealed some different staining reactions vs. the control in eosinophils, further support for a neoplastic process. However, low numbers of blasts in that animal were negative for all stains and the standard staining pattern of normal or neoplastic precursors in this species is not known. Definitive classification of leukemias in hedgehogs will require further testing and validation of different antibodies for cross-reactivity and more extensive characterization of cytochemical staining patterns in mature and immature hematopoietic cells.All datasets generated for this study are included in the article/Ethical review and approval was not required for the animal study because the diagnosis of leukemia/lymphoma was made through routine blood examinations in veterinary clinics with owners requests and agreement. All clinicopathologic examinations were requested and agreed by the owners to obtain accurate diagnosis and to select adequate treatment for individual animals. No experimental manipulation with potential harm to animals was performed. Written informed consent was obtained from the owners for the participation of their animals in this study.IK contributed to the clinical interpretations and description of cases in Japan. SC, DH-M, and TS contributed one case from the USA, performed the cytochemical staining and provided case details, images and description of results. MA was responsible for cytologic and histopathologic interpretation and was the lead author on the manuscript. All authors read and edited the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.