Inflammatory Bowel Disease

Distal small bowel is the most common site involved by Crohn’s disease (CD). The transmural nature of CD causes small bowel strictures, fistulas, and abscesses, which are the main clinical manifestations of CD. Although the histopathological features of CD have been well recognized, it is of importance for pathologists to understand the basic diagnostic features, diagnostic pitfalls, and recent advances in diagnosing and managing CD in small bowel. Although ulcerative colitis (UC) is considered as a disease restricted in colon, there are some changes in small bowel related to UC that are often seen by pathologists, such as backwash ileitis or pouchitis. Proper pathologic assessment of small bowel resection or biopsy samples in these patients is particularly important.