杯状の形態を呈した直腸カルチノイド腫瘍の1例

Rectal Carcinoid with Scyphoid Form, Report of a Case

要旨　症例は43歳，女性．下血を主訴に当センターを受診し，下部消化管内視鏡検査で下部直腸に深掘れの大きな陥凹を伴う亜有茎性の粘膜下腫瘍様隆起を指摘された．注腸X線検査では大きさ18mmの病変で，中央に境界明瞭な深い陥凹を伴う杯状の粘膜下腫瘍様隆起として描出され，可動性は良好であった．生検病理組織像にてカルチノイド腫瘍の診断が得られ，患者家族の強い希望で，まず経肛門的局所切除術を施行した．切除標本では，深部断端距離が500μm未満，核分裂像が2個/10HPF，Ki-67 L.I.が約3％，リンパ管侵襲もみられたため，直腸追加切除が行われた．その結果，リンパ節転移が陽性であった．本症例は直腸のカルチノイド腫瘍としては比較的まれな特異な形態を呈しており画像所見を中心に報告する．

　A 43-year-old woman visited our hospital with a complaint of hematochezia, and was found to have a polypoid lesion in the lower rectum. Radiography and colonoscopy showed a subpedunculated submucosal tumor, measuring 18mm in diameter, with a wide and deep depression on its surface. The lesion was diagnosed as carcinoid by histology of the biopsy specimen. At first, local transanal resection was performed in accordance with the will of the patient. Histological examination of the resected specimen revealed a possibility of positive margin (＜500μm), mitotic index 2/10 HPF, Ki-67 labeling index about 3％, and lymphatic invasion. Low anterior resection was added, and lymph node metastases were recognized. This case was considered a relatively atypical case of rectal carcinoid with scyphoid form.