Colonic Schistosomiasis: The Great Masquerade of Inflammatory Bowel Disease

Abstract

Case 1: A 23-year-old Ethiopian male presented with intermittent abdominal pain, tenesmus, blood, and mucus in his stool for three years. Abdominal CT showed questionable sigmoid wall thickening. Colonoscopy was performed with a provisional diagnosis of inflammatory bowel disease (IBD). Multiple rectal polyps were seen. The polyps and random biopsies showed granulomatous inflammation with mucosal eosinophilia and Schistosoma eggs. Case 2: A 68-year-old Ethiopian female was referred to gastroenterology for a one-year history of change in bowel habits. She underwent colonoscopy, which revealed multiple 5-8 mm polyps. All polyps were inflammatory, with tissue eosinophilia and focal crypt calcification suggestive of Schistosomiasis. Case 3: A 50-year-old Ethiopian male with a history of perianal fistula status post fistulotomy was referred for abdominal pain and bloody diarrhea suspect for Crohn's disease. Colonoscopy showed patchy areas of pustules in the transverse colon, which were biopsied. The pathology showed tissue eosinophilia with Schistosoma eggs. Case 4: A 57-year-old Filipino male was referred for screening colonoscopy. Biopsy of a yellow submucosal lesion showed a noncaseating granuloma with calcified eggs consistent with Schistosomiasis. Case 5: A 23-year-old Ethiopian male was referred for a two-year history of abdominal pain. He underwent colonoscopy with removal of a 6-mm polyp from the rectum and biopsy of a patchy area with whitish dots in the sigmoid colon. The rectal polyp was inflammatory, and the biopsy showed marked tissue eosinophilia with Schistosoma eggs. Discussion: Schistosomiasis is a parasitic disease affecting more than 200 million people worldwide; however, it is rare in the United States. Diagnosis is made by microscopic examination of stool for Schistosoma eggs. However, unlike in acute disease where the parasite sheds numerous ova, in chronic disease, ova passage in stool is scanty. The most common endoscopic findings are mucosal edema, hemorrhage, and ulceration in the early stages, and thickened bowel wall, polyps, and intestinal strictures in the late stages, mimicking inflammatory bowel disease, particularly Crohn's disease. Conclusion: Schistosomal colonic disease is becoming more common in the United States, due to immigration from endemic areas. Even though diagnosis is usually made by stool examination for ova and parasites, most immigrants presenting to clinics in the United States have chronic Schistosomal colitis, and thus, stool studies may be negative. Two of our patients presented with features suggestive of IBD, thus it is an important consideration in immigrants presenting with atypical features or non-resolving “inflammatory bowel disease”.