[Intracranial osteolytic hemangiopericytoma manifesting as a rapidly enlarging extracranial soft tissue mass lesion].

Hemangiopericytoma is a highly vascular and rapidly growing tumor, which tends to recur at distant locations. Complete surgical resection is often difficult because of intraoperative excessive hemorrhage or brain swelling. A 31-year-old male presented with intracranial osteolytic hemangiopericytoma manifesting as a rapidly enlarging extracranial soft tissue mass lesion causing a subcutaneous mass in the forehead. Computed tomography (CT) and magnetic resonance (MR) imaging demonstrated a lesion in the frontal lobe. Careful follow up was performed because the patient suffered no neurological deficits. The subcutaneous mass rapidly enlarged for 6 months. CT and MR imaging showed an osteolytic intracalvarial lesion with an extradural soft tissue component. Angiography demonstrated obstruction of the superior sagittal sinus and dense tumor staining with slow circulation and venous drainage. Gross total surgical resection was performed following endovascular embolization of the feeding arteries. Histological examination demonstrated an hemangiopericytoma. Although rare, hemangiopericytoma should be included in the differential diagnosis of rapidly enlarging subcutaneous mass. Preoperative endovascular treatment may allow less invasive surgery.