Clinicopathological Features and Pathological Diagnosis of Inflammatory Bowel Disease-Associated Cancer

Abstract

Ulcerative colitis (UC)-associated carcinoma and Crohn’s disease (CD)-associated carcinoma have distinct clinicopathological features. Concerning the site of carcinoma, UC-associated carcinoma has mainly occurred in the rectosigmoid area of total colitis type, and UC-associated carcinoma has a tendency to occur in multiple cancers of the colon. On the other hand, CD-associated cancers in Japan are predominantly solitary mucinous carcinomas occurring in the rectum and anus. The histological features of both types of carcinoma are similar and have variety, ranging from very well-differentiated adenocarcinoma to poorly differentiated adenocarcinoma with a background of dysplasia. Reflecting the variety of histology and the high degree of inflammation in the background, the gross image also shows a variety of complex morphologies, and the boundaries between them are unclear. In the following, we will review the morphological characteristics and pathological diagnosis of inflammatory bowel disease (IBD)-associated cancers with case examples.