Malignant hemangiopericytoma of the parapharyngeal space.

Hemangiopericytoma is a rare vascular neoplasm, occasionally occurring in the head and neck region. Diagnosis is made histologically, but even then, it is difficult to predict the behavior of the tumor in an individual patient. The patient described in this report presented with symptoms of parapharyngeal compression due to such a tumor. It is believed that malignant hemangiopericytoma has not been previously reported in this site.