The differentiation of amebic colitis from inflammatory bowel disease on endoscopic mucosal biopsies.

Background: Intestinal amebiasis is one of the important differential diagnoses of Inflammatory Bowel Disorders in areas where it is highly prevalent. Aim: Studies comparing the clinical, endoscopic and histological features of these disorders have never been done, so we undertook this study. Materials and Methods: A retrospective study comparing mucosal biopsies of 14 consecutive cases of intestinal amebiasis with 14 cases of Ulcerative colitis and 12 cases of Crohn’s disease. A total of 65 biopsies from patients with amebiasis, 56 biopsies from patients with Crohn’s disease and 65 biopsies of patients with Ulcerative colitis were reviewed. Results and Conclusions: Discrete small ulcers less than 2 cm in diameter in the cecum or rectosigmoid, with intervening normal mucosa, were the most common finding on endoscopy in patients with amebiasis. On histology, necrotic material admixed with mucin, proteinaceous exudate and blood clot lining ulcers, significant surface epithelial changes such as shortening and tufting adjacent to sites of ulceration, mild chronic inflammation extending into the deep mucosa and mild architectural alteration were features of amebiasis. Trophozoite forms of ameba were seen in the necrotic material lining sites of ulceration or lying separately, as well as over intact mucosa. Necrotic material lining ulcers was less common in IBD, but chronic inflammation, crypt abscess formation and architectural alteration were more severe.