Adenocarcinoma arising in Crohn's disease: report of two cases.

Crohn's disease of the colon and small bowel is associated with a greater-than-chance increased incidence of adenocarcinoma, which also differs from the norm in age and anatomic distribution. The cancer risk appears to rise with earlier age of onset and long duration of the granulomatous disease, and the prognosis is relatively poor, probably due to difficulty in diagnosis because of the overlapping Crohn's disease. Two additional cases of adenocarcinoma arising in Crohn's disease are described.