Small Bowel Lesions Mimicking Crohn's Disease

PURPOSE OF REVIEW: Not all injuries of the terminal ileum are Crohn's disease. It is the purpose of this review to consider the differential diagnosis of other acute and chronic ileal lesions. RECENT FINDINGS: The recognition of a granulomatous disease of the terminal ileum, distinct from tuberculosis, dates back over 85 years and perhaps much farther, but over the past decades, many other clinical pathologic entities have been described that are neither tuberculosis nor Crohn's eponymous regional enteritis. In recent years, the catalog of lesions mimicking Crohn's disease of the small bowel and proposals for differential diagnosis and treatment have expanded to include newly reported appendiceal pathology, primary cancers and lymphomas of the intestine, unexpected metastases from distant organs, unusual infections, vasculitides and other ischemic conditions, Behçet's disease, endometriosis, and drug reactions. A diagnosis of Crohn's disease should not be a reflex action in the face of small bowel structural or inflammatory lesions without consideration of pathology in adjacent organs, primary and metastatic lesions of the small intestine, infections, vascular diseases, infiltrative diseases, drug injury, or other "idiopathic" conditions.