Subfrontal Schwannomaの1例

Subfrontal Schwannoma ： Case Report

Ⅰ．はじめに

　頭蓋内に発生するschwannomaは原発性脳腫瘍中10.8％（von Recklinghausen病を含む）を占め，その多くが聴神経より発生する．稀に三叉神経，顔面神経，舌咽神経，迷走神経，副神経および舌下神経からの発生の報告があるが，subfrontal schwannomaの報告は極めて少ない．今回われわれは，olfactory groove meningiomaと鑑別を要したsubfrontal schwannomaの1例を経験したので報告する．

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.