When Treatment Becomes a Threat: A Report of a Rare Case of 5-Fluorouracil (5-FU)-Induced Enteritis Mimicking Inflammatory Bowel Disease

We report a rare case of 5-fluorouracil-induced enteritis mimicking inflammatory bowel disease (IBD). A 67-year-old man undergoing adjuvant chemotherapy for colon cancer developed profuse diarrhea and fever. Initial findings were suggestive of IBD; however, biopsy findings and clinicopathologic correlation supported a diagnosis of chemotherapy-induced enteritis. Cessation of chemotherapy and initiation of corticosteroids led to resolution of symptoms. Awareness of this rare complication can prevent misdiagnosis and inappropriate treatment.