確定診断が困難であった鼻腔原発悪性末梢神経鞘腫疑いの1例

A case of nasal tumor suspected of malignant schwannoma which finally remained undiagnosed.

はじめに

　悪性末梢神経鞘腫はSchwann細胞由来の腫瘍であり，頭頸部では前庭神経，迷走神経，横隔神経，頸部交感神経幹などに発症する。頭頸部領域のうち鼻腔内に発症する神経鞘腫は稀であり，悪性末梢神経鞘腫は少数の報告しかみられない。今回，われわれは鼻腔原発腫瘍を手術摘出し，病理組織検査で悪性末梢神経鞘腫が疑われたものの富細胞性神経鞘腫との鑑別が困難で確定診断に至らなかった稀な症例を経験したので，文献的考察とともに報告する。

　A 47-year-old man with a large tumor of the left nose is presented. The tumor was resectetd by endoscopic surgery. A routine pathological study suggested the tumor to be either malignant schwannoma or cellular schwannoma. For differential diagnosis, immunostaining was additionally performed to show Ki67 labeling index to be approximately 10％, and S100 protein to be strongly positive. These results could not distinguish the two possible diagnoses. The pathological diagnosis is still unconfirmed and the patient is followed up at our clinic 2.5 years after the surgery without any findings suggestive of recurrence.