Common site of regional enteritis is -

Crohn disease (Terminal ileitis or regional enteritis) Crohn disease (CD) is an inflammatory bowel disease, characterized by - Sharply delineated and typically transmural involvement of the bowel by an inflammatory process with mucosal damage. The presence of non-caseating granulomas. Fissuring with the formation of a fistula. Any portion of intention can be involved but most commonly small intestine is involved. Small intestine → 40% Small intestine + colon → 30% Colon → 30% Terminal ileum involved most commonly and rectum is usually spared. CD is associated with HLA-DM1/DQw5 and NOD 2 genes and an abnormal T-cell response, particularly CD4 + T cells (Th1 cells)