Subfrontal schwannoma: case report

Schwannoma are benign, slowly growing nerve sheath tumors. They can arise from any peripheral nerve containing Schwann cells including distal portions of cranial nerves. Intracranial schwannomas arising from a subfrontal lesion are very rare. We report a case of subfrontal schwannoma in a 38-year-old woman who presented with seizures in February 2003. MRI features resembled an olfactory groove meningioma. The left carotid angiography revealed that the tumor was supplied from the anterior ethomoidal artery, but no remarkable tumor stain was detected. Bifrontal craniotomy with total excision of the tumor revealed a tumor in the left subfrontal lesion. The tumor was attached to the falx, the left frontal lobe, and the skull base, but those structures were not invaded. Unfortunately, we could not detect the left olfactory nerve. Subsequent histological examination proved that this tumor was schwannoma. A review of the literature found 27 cases including this case previously described. Arguments are raised that schwannomas in a subfrontal lesion are comparable to or even occur as intracranial schwannomas with frontal localization. Subfrontal schwannomas are very rare. For this reason they have not been diagnosed preoperatively. Further cases of subfrontal schwannoma are necessary to solve the enigma of the origin of this tumor.