Surgical resection of sinonasal hemangiopericytoma involving anterior skull base: Case reports and literature review.

Hemangiopericytomas are soft tissue tumors composed of pericytic cells that are characterized by their "staghorn" vascular branching and their variable clinical presentation. Fifteen to 25% of all HPC occur in the head and neck, with only 5% found in the nose or paranasal sinuses. Sinonasal hemangiopericytoma (SNHPC) is considered distinct from its soft tissue counterpart - the former showing a more uniform cellular organization, has convincing pericytic differentiation and is associated with a far better prognosis. With less than 200 cases of SNHPC reported in the literature, only limited assumptions can be made about this rare tumor. The purpose of this article is to add to the growing body of literature on this disease. We report two new cases of SNHCP - both in female patients who presented with epistaxis and anosmia. Pulsatile vascular masses were visualized with nasal endoscopy - one in the left middle meatus and the second one near the cribriform plate. CT and MRI studies show enhancing masses in the left nasal cavities with thinning and erosion of the skull base. Diagnoses were confirmed by pathology which reported spindle cell neoplasm staining positively for VEGF, NSE, factor XIIIa, S-100 protein, and CD34, and negative for actin, desmin, CD31, and pankeratin, consistent with hemangiopericytoma. In one patient, embolization of the sphenopalatine and labial artery as well as pre-operative radiation therapy was performed before complete endoscopic resection was undertaken. The second patient had a tumor invading the skull base, so a craniofacial resection was performed. Both patients remained free of disease two years after surgery. Review of the literature and treatment options are discussed.