Adenosquamous-cell carcinoma in ulcerative colitis. Report of a case.

Three adenosquamous carcinomas and 2813 adenocarcinomas of the colon proximal to a line 7 cm craniad to the dentate line were treated between 1946 and 1986. Of these, one adenosquamous carcinoma and 42 adenocarcinomas were associated with ulcerative colitis. Therefore it was calculated that adenosquamous carcinoma occurs 0.07 percent as frequently as adenocarcinoma of the colon in the general hospital population and 2.4 percent as frequently in patients with ulcerative colitis, a 33-fold increase. It is concluded that, although adenosquamous-cell carcinoma of the colon is a rare tumor, its frequency in relation to adenocarcinoma increases in the presence of ulcerative colitis.