hemangiopericytomas ( hpcs ) were first categorized by stout as malignant tumors arising from the blood vessels and described as a sarcoma . the cell of origin is thought to be the pericyte which interacts with endothelial cells and is critical for blood vessel maintenance . hpcs are extremely rare and occur usually outside the central nervous system ( cns ) with the most common sites being the lower extremities or retroperitoneum . in rare instances , hpcs can arise from the meninges in the cns and can be confused with solitary fibrous tumors . in the case series by guthrie and et al . the primary mode of treatment included surgical resection , followed by radiotherapy , but , unfortunately , hpcs can both recur and metastasize . paraneoplastic syndromes have been reported as the initial presentation or part of the diagnosis of hpc . the paraneoplastic syndrome of oncogenic osteomalacia , defined by hypophosphatemia , hyperphosphaturia , and osteomalacia , has been seen in soft tissue sarcomas , including hpcs . while the roles of surgical resection and radiotherapy are well understood , the role of chemotherapy in the treatment of multiple recurrences of hpc has not been well established . we present a case of a male with a right sphenoid wing hpc who presented initially with the paraneoplastic syndrome of oncogenic osteomalacia 9 years before his hpc diagnosis . after multiple recurrences , he has been stabilized with molecularly targeted monotherapy utilizing dasatinib , a small molecule that inhibits src - related tyrosine kinases . a 22-year - old healthy male presented with diffuse bone pain . on clinical laboratory testing , serum phosphorus was extremely low at 0.8 mg / dl . the patient was later found to have hyperphosphaturia and hypercalcemia and was diagnosed with hypophosphatemic osteomalacia . etiology of the hypophosphatemic osteomalacia was unclear at that time , but the patient was treated with neutral sodium phosphate and dihydrotachysterol , which improved his pain . he also began to experience sharp pain at the right retro - orbital region and right - sided hearing loss . later , placement of a right tympanostomy was attempted because of presumed chronic otitis media and a vascular tumor was visualized in his right middle ear . initial biopsy was only remarkable for granular tissue . at 30 years of age , he developed numbness at the right temple and a head ct revealed a mass arising from the right sphenoid wing that infiltrated into the floor of the middle cranial fossa . embolization was performed which was followed by a partial resection of the mass via right temporal craniotomy . the previous diagnosis of hypophosphatemic osteomalacia was attributed to a paraneoplastic presentation of oncogenic osteomalacia due to hpc . within 4 years from initial tumor diagnosis , the tumor recurred , and the patient was found to have a right seventh nerve palsy . a second embolization was performed for this recurrent tumor , and the patient was followed with serial scans . approximately 3 years after this resection , the tumor increased in size . despite partial resection , he was also noted to have brown tumors associated with hyperparathyroidism involving the mandible and the right hand . octreoscan ( indium - labeled pentetreotide scan ) showed active uptake by the remaining tumor . after identification of the brown tumors , the patient underwent a total parathyroidectomy with reimplantation of one parathyroid into the left arm to address the tertiary hyperparathyroidism . after 3 years of octreotide treatment , he developed dj vu episodes ( consistent with possible seizure activity ) and magnetic resonance imaging ( mri ) revealed progression of his tumor . when the mass recurred approximately 2 years later , he had fractionated stereotactic radiotherapy to the right temporal mass . eleven months after fractionated radiotherapy , he participated in a clinical trial for 5 months using somatostatin receptor radiopharmaceutical called ( 90 ) y - dodecane - tetrateaacetic acid - phe1-tyr3-octreotide . after completion of 3 six - week cycles of this therapy , he was followed with serial mri scans . approximately 1 year later , he developed worsening right facial weakness and was found to have recurrent tumor extending into the middle ear cavity , external auditory canal , intratemporal fossa , inferior orbital fissure , and the anterior aspect of the cavernous sinus . there was no change in his treatment course and he continued to be followed with serial scans until 4 years later . at that time ( age 56 years ) , he underwent a right temporal craniotomy with partial resection for recurrent tumor ( fig . testing of his tumor from the second resection showed high immunoreactivity to platelet - derived growth factor receptor ( pdgfr ) , therefore , dasatinib was considered for monotherapy . after the third resection , he was placed on dasatinib at 70 mg orally once a day and has been followed with serial scans . currently , he has been on monotherapy with dasatinib for 2 years and continues to be both clinically and radiographically stable by mri an dfdg - pet ( fig . 2c ) . hpc is a rare malignancy that is believed to arise from pericytes , a support cell of the vasculature that interacts with endothelial cells . usually , hpcs present in the lower extremities or retroperitoneum , but in some circumstances , they can occur within the cns . when they involved the cns , hpcs were previously described as angioblastic meningiomas , as the tumors were uniquely vascular and arose from the meninges . . two case series of meningeal hpcs have described the presentation , course , and treatment of these rare tumors . in both case series , patients present in adulthood , with a median occurrence of hpc in the fifth decade . the initial presentation was usually focal neurological signs , and headache was also a prominent symptom that led to the diagnosis of meningeal hpcs . a majority of patients experienced recurrences of their tumors within a range of 60.6 - 76% . in rare circumstances , clinicians have documented that hpcs can metastasize with sites including the bone , liver , lung , and peritoneum , with a 5-year metastasis rate at 33% . treatment of meningeal hpcs is similar to meningiomas in that surgical resection is utilized at the initial presentation if amenable to surgery . total resection is often hindered by the extensive vasculature of the tumor , and pre - embolization of the tumor before resection can prevent blood loss . radiotherapy is used post - operatively to prevent recurrence , but in a study by dufour et al . doxorubin - based regimens have been used , but have yet to establish a clear role in the treatment of hpc . with the recurrent nature of hpcs as seen in our current case report , there is a vital need for better treatments of persistently recurrent hpcs . one possible therapy could be the use of molecularly targeted therapies based on the pattern of expression of growth factors in hpcs . a recent report showed that angiomatous meningiomas and hpcs often overexpress pdgfr as detected by immunohistochemistry . therefore , it is provocative that this overexpression of pdgfr could be utilized to treat recurrent angiomatous meningiomas and hpcs . dasatinib , at nanomolar concentrations , inhibits the following kinases : bcr - abl , src family ( src , lck , yes , fyn ) , c - kit , epha2 , and pdgfr . dasatinib is approved by the federal drug administration for the treatment of chronic myelogenous leukemia or philadelphia - chromosome positive acute lymphoblastic leukemia . in our case presentation , the patient 's tumor tissue showed overexpression of pdgfr based on immunohistochemical analysis . because of dasatinib 's ability to inhibit pdgfr , we initiated therapy with this agent . since initiation of therapy , the patient has tolerated that therapy well with little toxicity and has continued on monotherapy for over 2 years . mri and fdg - pet imaging reveal no evidence of recurrent disease at this time . thus , this suggests that there may be a role for targeted therapy in the treatment of hpcs . while this tumor is extremely rare and it is thus difficult to evaluate the drug 's effectiveness in clinical trials , the further use of dasatinib in the treatment of recurrent hpc may be warranted . in conclusion , our case report provides a first example of treatment of recurrent hpc with molecular targeted monotherapy .