31病巣を認めた多発直腸カルチノイドの1例

Multiple Rectal Carcinoid Tumors with 31 Lesions, Report of a Case

要旨　患者は71歳，男性．肛門部痛，肛門出血の精査目的に下部消化管X線検査および内視鏡検査が施行され，Ra～Rbに径5～10mmの立ち上がりはなだらかで表面平滑，半球状，辺縁整で類円形のIIa型隆起性病変の多発を認めた．表面は正常粘膜で覆われ，黄色調で頂部に微細な血管像を認めた．生検により多発直腸カルチノイドと診断し腹会陰式直腸切断術を施行．病理組織学的所見では31病巣を認め，いずれも粘膜下に存在した．深達度は最深のものでsm2であり傍直腸リンパ節に転移を認めた．直腸カルチノイドの多発例は極めてまれであり，本邦での報告例は27例のみである．多発例ではリンパ節転移率が高く，治療においては注意が必要である．

　A 71-year-old male visited our hospital because of anal pain and bleeding. Double contrast barium study of the lower rectum in the supine position showed multiple protruding lesions. In the front view, lesions ranging in size from 5 to 10mm were round and clearly demarcated. In the lateral view, the surface was smooth and hemispherical but no deformity of the colonic wall was demonstrated. Colonoscopic examination showed multiple protruding lesions in the lower rectum. The size of the lesions ranged from 5 to 10 mm. All the lesions were yellowish, hemispherical and classified as IIa-like submucosal tumors. The surface was smooth and covered with normal mucosa with fine vascularity. Biopsy specimens showed the tumor to be a carcinoid tumor. A diagnosis of multiple rectal carcinoid tumors was made and abdominoperineal excision was performed. Histologically, the resected specimen proved to be 31 carcinoid tumors with lymph node metastasis. Low-power view of the microscopic patterns showed carcinoid tumors located within the submucosal layer. Multiple rectal carcinoid tumors are rare, with only 27 cases having been reported in Japan. The incidence of lymph node metastasis is higher (22.7％) in multiple rectal carcinoid tumors than in isolated single tumors. Therefore, care should be exercised in treating multiple rectal carcinoid tumors.