腫瘍の露出により特異な形態を呈した直腸カルチノイドの1例

Carcinoid Tumor of the Rectum, Report of a Case

要旨　患者は48歳，女性．主訴は肛門出血．大腸内視鏡検査にて下部直腸に丈の高い隆起性病変を認めた．基部は健常粘膜に覆われ，隆起部には，まだらな発赤調で凹凸不整な腫瘍の露出を認め，その表面の拡大観察所見は工藤分類のV型(無構造)に相当した．超音波内視鏡検査にて深達度は粘膜下層までと判定，近傍のリンパ節の腫大は認めなかった．生検にてカルチノイドと診断され，直腸低位前方切除術と所属リンパ節郭清(D₁)を施行した．切除標本で腫瘍の大きさは16×15×11mmで粘膜下層までにとどまるカルチノイドであり，リンパ節転移は認めなかった．本症例はカルチノイドの発育過程で被覆上皮が脱落したために腫瘍が露出し特異な形態を呈したと考えられ，興味ある症例であった．

　A 48-year-old female visited our hospital because of anal bleeding. Endoscopic examination revealed a protruding lesion in the rectum. The base of the lesion was covered with normal mucosa but the tumor with a red-dish, irregular surface was able to be seen on the top of the lesion. Using magnifying colonoscopy, we observed according to the classification of Kudo, a non-structured pattern (Type V) at the surface of the tumor. Additional endoscopic ultrasonography revealed that the depth of tumor invasion extended to the submucosal layer, but no lymphnode swelling was detected. Endoscopic biopsy revealed a carcinoid tumor, and lower anterior resection and regional lymphnode resection were performed. The resected specimen was 16×15×11 mm in size and microscopic examination confirmed that it was a carcinoid tumor with invasion limited to the submucosal layer. No lymphnode metastasis was detected. It seems that during the course of the tumor growth, the normal mucosa covering the tumor was stripped away and the irregular, nodular surface appeared. We report a case of carcinoid tumor of the rectum which was very intersting for its peculiar shape.