Terminal Ileitis : Crohn's disease is not always the diagnosis

• Terminal ileum may be inflamed in patients with ulcerative colitis (backwash ileitis)

Infections:

• Tuberculous ileitis : the ileum is the most commonly affected site part of the small bowel in abdominal tuberculosis.

• Yersinia enterocolitica ileitis

• Mycobacterium avium-intracellulare complex infection : ileitis in patients with advanced stages of HIV infection

• Lymphoid hyperplasia : benign reactive process. Focal lymphoid hyperplasia of the terminal ileum may rarely cause terminal ileitis

• Small bowel lymphoma

• Carcinoid tumors 

• NSAID enteropathy is usually asymptomatic, although some patients present with iron deficiency anemia, perforation or strictures

• Isolated terminal ileum ulcerations

Terminal ileitis may also occur in association with these conditions:

• Collagenous and lymphocytic colitis
• Henoch-Schönlein purpura       
• Eosinophilic gastroenteritis 
• Systemic mastocytosis
• Sarcoidosis 
• Endometriosis