Amebic colitis can mimic tuberculosis and inflammatory bowel disease on endoscopy and biopsy

Biopsies of 11 patients with histopathologically diagnosed amebic colitis was evaluated; endoscopically, they were suspected to have tuberculosis or inflammatory bowel disease. Amebiasis was suggested in the differential diagnosis in only 3 cases. Three patients had purely rectal or sigmoid involvement, whereas the others had ileocecal, cecal, ascending, or transverse colon disease. The biopsies showed cryptitis and depletion of mucin but no crypt branching. Crypt abscesses were seen in one biopsy. Trophozoites of Entamoeba histolytica were seen in the exudate in all cases. The trophozoites were round to oval, approximately 25 to 40 microm in diameter and had a single, round nucleus and periodic acid-Schiff-positive cytoplasm. Phagocytosed erythrocytes were present in the trophozoites. Some features of ulcerative colitis and infectious colitis, such as cryptitis and crypt abscesses, are also seen in amebic colitis. Amebic colitis must be included in the differential diagnosis of all patients with suspected inflammatory bowel disease and tuberculosis.