Olfactory groove schwannoma--case report.

A 30-year-old man presented with a 2-year history of intermittent headache. No neurological deficit was detected. Computed tomography (CT) and magnetic resonance imaging showed a tumor with a diameter of 2.5 cm in the left anterior skull base associated with bone scalloping on three-dimensional CT. Angiography showed a hypovascular tumor. Craniotomy demonstrated a tumor in the region of the left olfactory groove attached to the anterior part of the cribriform plate. The histological diagnosis was schwannoma. Schwannoma arising from near the olfactory groove is rare, with only 13 other cases reported. The precise origin of these tumors is not well understood, but the tumor in this case probably arose from the fila olfactoria, because the olfactory bulb was involved in the tumor, whereas the olfactory tract remained intact.