Hemangiopericytoma/Solitary Fibrous Tumor of the Parietal Bone: A Case Report

Hemangiopericytoma/solitary fibrous tumor (HPC/STF) is a rare tumor arising from Zimmerman's pericytes and it is characterized by an aggressive malignancy, with a high tendency for local and distant recurrence. The authors report the case of a middle-aged woman with HPC/SFT of the right parietal bone, which is an extremely rare primary location of involvement. The patient presented with a painful deformity of insidious growth at the right parietal region. Assessment with cranial computed tomography scan and magnetic resonance imaging revealed an expansive lesion at the right parietal bone, with exocranial extension and 27 mm of maximal diameter. Craniotomy with gross tumor removal, duraplasty, and cranioplasty was performed, and the diagnosis of HPC/SFT, WHO grade III, was established by pathological and immunohistochemical analysis. The patient was then evaluated for adjuvant radiation therapy and received a dose of 60 Gy (2 Gy/fraction) with 3D conformal radiotherapy to the surgical bed. The adjuvant treatment was uneventful and, after 8 months of follow-up, there was no suspected local or distant recurrence. The rarity of this diagnosis, its aggressive behavior, and the lack of published data posed several challenges for the treatment management.