直腸肛門部の腫瘍性疾患―直腸肛門部の上皮性腫瘍

Epithelial Tumors of the Anal Canal

要旨　肛門癌は比較的まれな疾患であるが，組織学的には多彩なものがある．これは肛門管が直腸と肛門周囲の皮膚との間にあって，発生学的・解剖学的に種々の上皮が入り交じっており，また歯状線の上方にはcloacaに由来するcloacogenic zoneがあり，さらには歯状線には肛門腺が開口しているなど，これらの多様な組織が肛門癌の発生母体となっていることに由来している．本稿ではこのなかから代表的な9種，すなわち，肛門管早期癌，痔瘻癌，Crohn病に合併した痔瘻癌，腺扁平上皮癌，類基底細胞癌，基底細胞癌，肛門部Paget病，Bowen病，悪性黒色腫について症例報告を加えて述べる．

　Although anal carcinoma is relatively rare, there are many histological types. The reason for this is that the anal canal is situated between the perianal skin and the rectum, which is covered with the anoderm composed of a mixture of various epithelia.

　In addition, there is the cloacogenic zone above the dentate line, originating from the cloaca, and there are the anal glands opening at the dentate line.

　In this paper we will describe the following nine types of anal carcinoma i.e., early anal carcinoma, fistulous cancer, fistulous cancer originating from Crohn's disease, adenosquamous carcinoma, basaloid carcinoma, basal cell carcinoma, extramammary Paget's disease,Bowen's disease, and malignant melanoma, along with their case reports.