痔瘻癌の病理学的特徴

Pathological Features of Carcinoma within Anorectal Fistula

要旨●痔瘻癌は難治性痔瘻を母地として生じるまれな癌である．今回，筆者らは痔瘻癌80例を解析し，その病理学的特徴を明らかにした．肉眼型は筆者らが提唱した，①管外型，②突出型，③潰瘍型の3型に分類した．それぞれほぼ同数で，潰瘍型は進行例や低分化な組織型が多い傾向があった．組織型は，これまでの報告同様，粘液癌が大半を占めた．免疫染色の結果では，CK7が大腸癌より陽性率が高く，ムチン抗体は大腸の粘液癌と類似した所見だった．p53の陽性例と陰性例では異なる特徴がみられた．Crohn病に合併した痔瘻癌は，臨床病理学的に特徴があることが報告されている．今後も症例の蓄積を通してさらなる解析が必要である．

　CAF（carcinoma within anorectal fistula）, a rare tumor, develops from the chronic anorectal fistula. We studied the pathological features of CAF by examining 80 CAF cases. We proposed three macroscopic types for CAF：extraluminal, exposed, and ulcerative. Notably, all three CAF types were detected at approximately the same portion. The ulcerative-type CAF tended to be more advanced and poorly differentiated. Mucinous adenocarcinoma was the most frequent histological type. Immunohistochemically, CK7 expression of adenocarcinoma within anorectical fistulae was higher than that of conventional colorectal adenocarcinoma. Mucin phenotype was similar in these two types of tumor. Different pathological features were detected between the p53-positive and -negative cases. The differences in the clinicopathological characteristics between CAF-associated and -unassociated Crohn's disease are previously reported.