Hemangiopericytoma of the temporal bone.

Hemangiopericytomas are uncommon soft tissue tumors. While their occurrence in sinuses and soft tissues around the ear is well documented, there are no reports of primary involvement of the temporal bone. This article discusses the case of a 21 year old patient who had a right temporal angioblastic meningioma resected and presented two years later with a hemangiopericytoma that extensively involved the right temporal bone and external auditory canal. In review, the "meningioma" had the same histological features as the auditory tumor and it was evident that both lesions resulted from the growth of a hemangiopericytoma arising from the intracranial aspect of the temporal bone. Electron microscopic examination of the tumor proved useful in making the diagnosis and in evaluating the cytological features that influence prognosis and treatment. Temporal bone involvement was a major problem and the opportunity is taken to document this rare occurrence and to discuss the biological behavior, pathological characteristics, and differential diagnosis of these neoplasms.