Crohn Disease (Regional Enteritis; Granulomatous Ileitis; Granulomatous Ileocolitis) By Aaron E Walfish, MD, Mount Sinai Medical Center; Rafael Antonio Ching Companioni, MD, HCA Florida Gulf Coast Hospital Reviewed / Revised Jan 2022 | Modified Sep 2022 View Patient Education Pathophysiology Symptoms and Signs Diagnosis Prognosis Treatment Key Points More Information Topic Resources Crohn Disease Activity Index... Crohn Ileitis Small-Bowel Follow-Through... Ulcer of the Ileum in Crohn... Barium Enema Showing Mucosal... Overview of Crohn Disease Crohn disease is a chronic transmural inflammatory bowel disease that usually affects the distal ileum and colon but may occur in any part of the gastrointestinal tract.