耳下腺内顔面神経鞘腫の1例

A case of facial nerve-derived schwannomas in the parotid gland

はじめに

　耳下腺腫瘍は日常診療でよく遭遇する疾患であり，多くの施設で手術が行われている。耳下腺良性腫瘍の多くはワルチン腫瘍または多形腺腫であり，顔面神経鞘腫は全体の0〜2.4％^1）と報告される稀な疾患である。今回われわれは，細胞診で多形腺腫疑いであったが，手術中に下行枝由来の顔面神経鞘腫と判明した耳下腺内顔面神経鞘腫の1例を経験したので報告する。

　Facial nerve-derived schwannomas are rare parotid tumors. Their preoperative diagnosis is difficult, especially in the absence of paralysis. We report here a case of facial schwannoma confined to the descending branch that was discovered during the operation. The tumor was resected by intercapsular resection while preserving the facial nerve using nerve integrity monitoring（NIM）. To date, only two cases of tumors in the descending branch region have been reported in Japan. The optimal treatment method should be selected considering the neurological deficits and the difficulty in diagnosing the tumors preoperatively.