悪性変化を示した巨大粉瘤の1例

Squamous Cell Carcinoma Arising in a Giant Atheroma. Case Report

　46歳，男性．10年前より殿部に無症候性の腫瘤を自覚していた．ここ数年で増大傾向を認めた．13×15cmの弾性軟から一部硬の巨大な腫瘤が存在し，MRIでは嚢腫壁から隆起する充実性の病変を認めた．拡大切除術を行い，病理学的検索で嚢腫壁から連続的に発生する高分化型扁平上皮癌を認めた．局所放射線療法を追加したが，患者は2カ月後に肺多発転移による呼吸不全のため死亡した．長期にわたり存在し，短期間に増大傾向を示す粉瘤には悪性変化の可能性があり，慎重な病理学的検索が必要である．

　A 46-year-old man with a lump 13×15cm in the left buttock for more than 10 years was found in MRI to have a tumor well-defined with a septal wall and a small proximal lesion showing contrast enhancement. Wide excision of the tumor was done. Histological examination of the specimen showed a voluminous edidermoid cyst with foci of in situ well-differentiated squamous cell carcinoma continuous with the cystic wall. About two months after surgery, the patient died due to multiple lung metastasis. It is frequently reported that malignancy should be suspected in cysts undergoing a change in character, such as increased size or pain. We therefore emphasize the importance of thoroughly examining large cysts several years old at potential sites of chronic irritation such as the buttocks.