Meningeal hemangiopericytoma: defining the role for radiation therapy.

Meningeal hemangiopericytoma is a rare neoplasm arising from perivascular pericytes. Accounting for < 1% of all brain tumors, these neoplasms are characterized by a high local recurrence rate and metastatic potential. Meningeal hemangiopericytoma occur most frequently during the fifth decade of life, with an almost equal sex incidence. To evaluate and define the role for primary, postoperative, or palliative radiotherapy in meningeal hemangiopericytoma, data were gathered from our own tumor registry and compiled with an extensive analysis of published series and case reports. This analysis reveals a 90%, 9 year actuarial risk for local recurrence following surgical resection only. Interestingly, less than 33% of these recurrences were noted within the first five years, which may account for the false assumption that these tumors are highly curable with surgical resection only. Radiation therapy appears to reduce this local recurrence rate, prolonging disease-free and overall survival. Radiation responses are dose dependent, with > 50 Gray providing superior long-term disease-free survival. Meningeal hemangiopericytoma are characterized by a slow, but progressive radiographic response to ionizing radiation, not unlike other radiated, highly vascular brain lesions, such as arteriovenous malformations. A retrospective review of clinical demographics, sites of meningeal origin, radiographic and pathologic findings and the role of chemotherapy is also presented.