慢性甲状腺炎に眼瞼外毛根鞘癌を認めた1例

A case of tricholemmal carcinoma with chronic thyroiditis

　81歳女性の左外眼角部腫瘤に対して腫瘍切除術を施行し，病理組織学的に検討を加えた。組織像として，角化異常や腫瘍細胞の柵状配列など表皮性悪性腫瘍の所見を呈し，かつ毛嚢開口部類似の陥凹部に胞巣を形成し，外毛根鞘由来のclear cellで構成されていたため，眼科領域では極めて稀な外毛根鞘癌と診断した。外毛根鞘癌はその組織学的類似性から，基底細胞癌や扁平上皮癌と鑑別する必要がある。一方，多発性外毛根鞘腫に甲状腺機能異常などを認めるCowden病が知られているが，本症例が慢性甲状腺炎を伴っており，免疫能との関連性からも興味深い点と思われた。

A tumor in the left outer canthus of an 81 year-old-female was resected. Pathological examina-tion revealed keratonosis, palisading, and nest formation of tumor cells, and consisting of clear cells derived from the outer hair sheath. Tricholemmal carcinoma, which is quite rare in the field of ophthalmology, resembles basal cell carcinoma and squamous cell carcinoma in its histological appearances. It is logical to assume that careful observation in necessary in distinguishing between this tumor and basal or squamous cell carcinoma. This patient with tricholemmal carcinoma also had hypothyroidism due to Hashimoto's disease, showing similarity to Cowden's disease, which is multiple tricholemmoma with thyroid gland involvement.