soft tissue sarcomas are rare tumors ( 1% of all adult malignancies ) with a dismal prognosis . approximately 70% of sarcomas occur in the extremities ( 49% in the lower and 19% in the upper limbs ) , while the remaining 30% occur in the trunk , abdomen or retroperitoneum ( 1,2 ) . among the most common histological types of sarcomas of the extremities , malignant fibrous histiocytoma ( mfh ) is the one exhibiting the highest incidence , followed by liposarcoma , fibrosarcoma and neurofibrosarcoma , with a peak incidence in the sixth decade of life . according to the world health organization 2002 classification of soft tissue tumors ( 3 ) , mfh may be categorized into three morphological subtypes : i ) storiform - pleomorphic mfh ( undifferentiated high - grade pleomorphic sarcoma ) ; ii ) giant - cell mfh ( undifferentiated pleomorphic sarcoma with giant cells ) ; and iii ) inflammatory mfh ( undifferentiated pleomorphic sarcoma with prominent inflammation ) ( 3 ) . mfh is also considered by the american joint committee on cancer to be a high - grade sarcoma by definition and , therefore , exhibiting high local aggressiveness . the typical histological appearance of mfh is that of a hypercellular neoplasm , with marked nuclear and cytological pleomorphism , bizarre appearance of stromal cells and a fascicular or storiform model growth ( 4 ) . the presence of a lesion suspicious for soft tissue sarcoma should prompt the surgeon to perform diagnostic - instrumental tests . x - ray may reveal ectopic calcifications in the surrounding tissues ( 520% ) , sclerosis or clear erosion of adjacent bone due to tumor compression . magnetic resonance imaging ( mri ) may reveal a lobulated mass , with intermediate signal in both t1 and t2 images ( 5,6 ) . there are also frequent intracapsular areas of tumor necrosis and hemorrhage , which are occasionally so extensive that the tumor is mistakenly diagnosed as hematoma of the soft tissues ( 7 ) . a correct surgical approach is crucial in several tumors , as previously demonstrated by our studies ( 8,9 ) , and a survey of the literature suggests that surgery is the first choice for the treatment of mfh ( 10 ) . owing to advances in surgical techniques , the advanced reconstructive methods and the development of effective adjuvant therapies , the use of widely demolitive surgery is now considered unnecessary . over the last few decades , studies have demonstrated that conservative surgery , with or without adjuvant therapy , appears to be an effective treatment for sarcomas , including high - grade sarcomas , with a local recurrence rate of 715% , with no significant differences in terms of overall survival and disease - free interval compared with amputation ( 1113 ) . neoplastic infiltration of the resection margins at the end of surgery appears to be among the major factors affectng the rate of local recurrence . in fact , the local recurrence rate approximates 13% with margins of < 1 cm , while it may be reduced to 0% in cases with margins of > 1 cm . in light of these data , amputation may no longer be considered to be the primary approach for the treatment of sarcomas of the limbs , but rather be reserved for those cases in which adequate resection can not be achieved without severe aesthetic and functional deficits , or when the sarcoma is very proximally located in the limb . the functional compartmental resection represents the surgical evolution of amputation , although not without functional consequences . however , the literature over the last 20 years reveals that soft tissue sarcomas of the extremities and precisely localized within a muscle may be treated by excision of the entire affected muscle , with preservation of the surrounding innervated muscles , without performing total compartmental resection ( 14 ) . the present study stems from a multidisciplinary management involving a team with expertise in general microsurgery , where microsurgical technique is routinely applied by the use of magnification devices such as loupes 4.5 , operating microscope 440 , dedicated instruments and led coaxial light . a 79-year - old caucasian man presented with a swelling in the middle third of the dorsal aspect of the left forearm . a core needle biopsy previously performed in a different hospital had not reached a definitive diagnosis . the patient also reported history of trauma 6 months earlier , with progressive volume increase , without pain or functional deficit . on clinical examination , the patient had a tense elastic 5-cm swelling in the dorsal aspect of the left forearm ( fig . 1 ) , hypomobile in the deep region , while the overlying skin appeared to be normal . the tinel 's sign and other tests assessing the functionality of the muscles and tendons of the hand and fingers were negative . the patient reported a dull pain elicited by palpation of the region in question and was subjected to instrumental diagnostic examinations . ultrasound imaging revealed a heterogeneous lesion with hyperechoic areas , perilesional hypervascularization and intralesional spots on signal - enhanced color doppler sonography . an mri revealed a neoformation sized ~84 cm within the extensor digitorum communis ( edc ) muscle , without invasion of the interosseous space ( fig . furthermore , the patient was subjected to total - body computed tomography ( ct ) staging that was negative for lymph node involvement or distant metastases . finally , electromyography ( emg ) was performed with normal findings , thus excluding any nerve compression or infiltration . as the case history , physical examination and diagnostic tests were strongly suggestive of a tumor , we decided to perform an open biopsy according to the criteria of enneking et al ( 15 ) . this procedure was performed under temporary ischemia of the arm , applying a tourniquet for 20 min at 220 mmhg at the root of the arm . the bioptic specimen included skin , subcutaneous tissue , fascia , muscle and a portion of the tumor that appeared to be localized inside the muscle . on histological examination , the neoformation exhibited irregular margins and consisted of spindle cells with nuclear atypia set in a dense , sclerotic , richly vascularized stroma , as evidenced by cd34 staining . on immunohistochemical staining , the tumor was positive for cd68 and negative for smooth muscle actin ( sma ) and s-100 . the proliferative index , as assessed by ki-67 , was 40% of the neoplastic elements . thus , the final diagnosis was mfh . based on the histological findings , mri imaging and in accordance with the national comprehensive cancer network ( nccn ) guidelines ( 16 ) , we decided to remove the tumor by excising the extensor compartment of the forearm with subsequent tendon transfer . indeed , the guidelines suggest radical surgical treatment followed by radiotherapy for such soft tissue sarcomas . a wide longitudinal incision was performed that also removed the scar of the earlier biopsy ( fig . surgery was performed by a microsurgical technique under magnification ( loupes 4.5 ) and the use of dedicated instruments and bipolar coagulator , allowing the identification of the correct anatomical cleavage planes and the preservation of the sensory branches of the radial nerve . according to the mri findings , the tumor was considered to be localized within the edc muscle ; however , the surgical exploration revealed that the lesion was located at a deeper plane , within the abductor pollicis longus muscle ( apl ) . the muscle fibres appeared to be subverted and discontinued , while the apl muscle sheath did not exhibit macroscopic discontinuity or pathological adhesions to the adjacent and overlying muscles ; the underlying bones did not appear to be infiltrated ( fig . 3 ) . therefore , we decided to change the surgical strategy and perform a wide excision of the tumor , including the apl muscle , without discontinuing the intact muscle sheath and the tumor pseudocapsule ( fig . 4 ) , thus preserving the edc muscle . subsequently , through a palmar mini - incision , we performed a transfer of the palmaris longus ( pl ) tendon to the distal apl metacarpal tendon insertion with a pulvertaft suture , in order to restore the abduction function of the thumb . the histological examination revealed an encapsulated , whitish neoformation , sized ~94.5 cm , with regular margins . 5 ) with nuclear atypia set in a dense , sclerotic , richly vascularised stroma , as evidenced by cd34 staining . on immunoistochemical staining , the proliferative index , as assessed by ki-67 , was 40% of the neoplastic elements . the mfh was classified as stage iib ( pt2b , pn0 , pm0 , g2 and r0 ) according to the american joint committee on cancer ( 7 ) . after 2 weeks , the recovery of the strength and functional ability of the hand and thumb was satisfactory , compared to the contralateral side . after 2 months of rehabilitation , there was no functional deficit in the abduction of the thumb . in accordance with the nccn guidelines ( 16 ) , we consulted the oncologist and the radiologist , who did not suggest any adjuvant therapy , also taking into consideration the patient 's comorbidities ( prostate cancer , heart disease and chronic obstructive pulmonary disease ) . moreover , the patient was informed of the options of adjuvant radiation therapy vs. observation and he selected observation . the patient has been followed up every 6 months for 4 years with clinical and instrumental examinations and he remains alive and recurrence - free . the diagnosis of soft tissue sarcomas located in the extremities is frequently delayed , as the tumor often grows slowly and is not associated with specific symptoms , apart from tension in the movements of the limb . in the present case , the open biopsy according to the criteria of enneking ( 15 ) established the diagnosis of mfh . the biopsy usually represents a strategy and not a small surgical intervention , therefore it is essential to first perform ultrasound , mri or ct examinations to limit the risk of a biopsy procedure . a biopsy performed incorrectly may negatively affect subsequent therapy , increasing the risk of local recurrence and postoperative complications , worsening the functional outcome . according to the mri findings therefore , surgery was planned to excise the tumor along with the edc , which would mean complete detachment of digit tendons and severe functional damage . accurate surgical dissection allowed us to identify the incorrect localization diagnosed by mri , i.e. , the sarcoma was unusually and unexpectedly located within the apl muscle . therefore , we performed a wide excision of the sarcoma , including the apl muscle , without discontinuing the intact muscle sheath and the tumor pseudocapsule , preserving the edc muscle . simultaneous pl tendon transfer was performed , to restore the abduction function of the thumb . the surgical excision and reconstruction were performed by the same microsurgical team through the application of a microsurgical technique and the functional outcome was excellent . the follow - up at 4 years did not reveal tumor recurrence or metastatic spread . in conclusion , when the sarcoma is entirely enclosed within a muscle , with free margins and without regional or distant metastases , a wide excision maintaining the muscle sheath intact may be considered as the optimal treatment .