Mass-forming ischemic colitis mimicking colon cancer

Rationale: Ischemic colitis is the most common form of intestinal ischemia, typically affecting elderly individuals with vascular risk factors such as hypertension, diabetes mellitus, atherosclerosis, and chronic kidney disease. In rare cases, a mass-forming variant may mimic malignancy or inflammatory bowel disease, creating a diagnostic challenge. We report a case of mass-forming ischemic colitis, initially suspected to be colon cancer, in which the correct diagnosis was established through short-term follow-up colonoscopy with biopsy, thereby preventing unnecessary surgical intervention. Patient concerns: A 75-year-old female presented with acute right upper quadrant abdominal pain. Her medical history included hypertension, diabetes mellitus, unstable angina, and chronic kidney disease. Abdominal CT revealed a mass-like lesion at the hepatic flexure without definitive colonic obstruction. The initial diagnosis was a suspicion of colon cancer. Colonoscopy revealed an ulcerofungating mass-like lesion with significant luminal narrowing, and the colonoscope could not pass through. However, the biopsy did not reveal any evidence of colon cancer. A follow-up colonoscopy with biopsy was performed 3 days later. The lesion showed macroscopic improvement, and the colonoscope could be advanced beyond the hepatic flexure. The biopsy result was consistent with ischemic colitis. Diagnoses: A diagnosis of mass-forming ischemic colitis was established. Interventions: She was treated conservatively with bowel rest, intravenous fluid therapy, and empirical intravenous ceftriaxone. Outcomes: Her abdominal pain gradually improved, and oral intake was resumed without complication. She was subsequently discharged in stable condition. A follow-up colonoscopy 2 months later demonstrated near-complete resolution of the previous lesion. Lessons: In the absence of colonic perforation or obstruction, short-term follow-up colonoscopy and biopsy helped distinguish mass-forming ischemic colitis from colon cancer, avoiding misdiagnosis and unnecessary surgery.