Table 6.

Chronic ileitis pattern: Etiologic Associations

Idiopathic Inflammatory Bowel Disease

Crohn’s Disease & Ulcerative colitis

Infections

Persistent infections Tuberculosis Yersinia

Drugs

NSAIDs Chemotherapeutic agents Sprue-like or AIE-like mucosal inflammatory process (Ipilimumab, PD-1/PD-L1 inhibitors, Olmesartan)

Radiation-induced changes

Crohn’s disease-like

Microscopic colitis associated ileitis

Behçet’s Disease

Non-specific isolated ulcers of the terminal ileum

Ileitis not otherwise specified

Changes secondary to the ileostomy

Underlying mass lesions Primary tumors, metastatic malignancies, endometriosis