食道表在癌に類似した拡大内視鏡像を呈した黒色調の肛門管扁平上皮癌の1例

Squamous Cell Carcinoma of the Anal Canal with Heterogeneous Blackish Pigmentation and Magnifying Endoscopic Findings Similar to Those of Esophageal Cancer, Report of a Case

要旨　患者は60歳代後半，女性．スクリーニングの大腸内視鏡検査を施行したところ，直腸肛門部に1/3周性の不整形の扁平隆起性病変を認めた．病変は口側では褪色調，肛門側では灰白色〜黒色を呈していた．拡大観察ではloop状血管と非loop状血管が混在し，さらに小型の無血管野を認めた．粘膜内病変と考え，ESDにて一括切除した．病理診断は，cancer of the anal canal，Type 0-IIa，35×10mm，squamous cell carcinoma，pM，ly0，v0，HM0，VM0であった．腫瘍は粘膜内に発育し，内部に黒色顆粒の沈着が認められた．

　A female in her 60s underwent a screening colonoscopic examination. Colonoscopy showed a flat-elevated tumor in the anal canal. The color of the lesion was whitish on the oral side and blackish on the anal side. Magnifying colonoscopy showed loop-like microvessels and nonloop microvessels that had formed small avascular areas in the lesion. We diagnosed the lesion as intramucosal cancer and performed endoscopic submucosal dissection for en bloc resection. Pathologically, the tumor was diagnosed as squamous cell carcinoma of the anal canal, type 0-IIa , size 35×10 mm, pM, ly0, v0, HM0, VM0. In addition, some melanin granules were deposited in the tumor.