A Rare Large Colonic Xanthoma Mimicking Neoplasia in a Young Adult: An Unusual Finding During an Iron Deficiency Anemia Workup.

Colorectal xanthomas are rare, benign lesions characterized by collections of foamy histiocytes within the lamina propria. Although commonly seen in the stomach, their occurrence in the colon is exceedingly uncommon and can mimic neoplastic or serrated lesions endoscopically. We report the incidental discovery of a large colorectal xanthomatous polyp in a 37-year-old male undergoing colonoscopy for the evaluation of persistent iron deficiency anemia. A sessile, pale-white lesion measuring 20 mm × 20 mm with a smooth surface and central depression was identified in the descending colon and resected via endoscopic mucosal resection (EMR). Histopathologic examination revealed foamy histiocytes positive for CD68 and negative for S100, consistent with a xanthoma. This case highlights the importance of considering xanthoma in the differential diagnosis of atypical-appearing colonic polyps and underscores the need for histologic confirmation to avoid overtreatment.