Ancient Schwannoma at the Olfactory Groove Mimicking Meningioma: A Case Report

Abstract

Schwannomas are benign slow-growing nerve sheath tumors that can develop in any peripheral or central nerve that contains Schwann cells. Most intracranial schwannomas arise from the vestibular, trigeminal, lower cranial, or facial nerves, in descending order. Theoretically, schwannomas cannot develop from the optic or olfactory nerves because they lack a Schwann cell layer (1). The origin of schwannomas located at the olfactory groove remains uncertain, but, they are thought to arise from branches of the first division of the trigeminal nerve or from the fila olfactoria (2). Solitary olfactory groove schwannomas are extremely rare and often preoperatively misdiagnosed as meningioma. In addition, ancient schwannoma is a rare variant that usually has a deep location with prolonged duration (3). To the best of our knowledge, there is no report of the radiologic findings of ancient schwannoma located at the olfactory groove.