外耳道中耳に生じた巨大角化性腫瘍の1例

Malignant Proliferating Trichilemmal Tumor in the Middle Ear and External Auditory Canal:Report of a Case

　I．はじめに

　中耳の角化性病変には真珠腫性中耳炎，外耳道真珠腫，keratosis obturans，扁平上皮癌などがある。扁平上皮癌はしばしば頭蓋内進展をきたし不幸な転帰をとるが，真珠腫性中耳炎でも再発性，難治性の経過をとり，頭蓋内進展をきたした症例が報告されている^1〜10）。

　われわれは外耳道，中耳に発生し，良性の病理組織を呈しながらも再発を繰り返し，最終的に腫瘍が頭蓋内進展をきたし，剖検病理所見より悪性増殖性外毛根鞘性腫瘍（malignant proliferatingtrichilemmal tumor）と診断された1例を経験したので若干の考察を加えて報告する。

A 60-year-old man who underwent 7 times of radical mastoidectoy in 34 years, was suspected of having cholesteatoma or benign tumor. The tumor, however, was progressive and proliferative, and finally invaded into the labyrinth, sphenoid sinus, middle and posterior fossa.

Histopathological examination revealed trichi-lemmal keratinization and atypical clear cells, and diagnosis of malignant proliferating trichilem-mal tumor was made. Differential diagnosis with cholesteatoma in the middle ear, external audi-tory canal cholesteatoma, keratosis obturans and squamous cell carcinoma was discussed.