P2255 - Occult Presentation of Amebic Colitis

Nirali Sheth, DO¹, Vennis Lourdusamy, MD¹, Ahmed Al-Khazraji, MD², Bhanu Singh, MD¹, Joshua Aron, MD², Raghav Bansal, MD, FACG², Aaron Walfish, MD^1
1Icahn School of Medicine at Mount Sinai (Elmhurst Hospital Center), Elmhurst, NY; ²Elmhurst Hospital Center, Elmhurst, NY

Introduction: Entamoeba histolytica (E. histolytica), a parasite endemic to developing nations, is the second leading cause of parasitic death worldwide. About 90% of individuals with amebic colitis are asymptomatic, but misdiagnosis can cause disseminated disease and high mortality. With the rising incidence of Inflammatory Bowel Disease (IBD) worldwide it is important to differentiate it from infectious colitis. We present a case of amebic colitis presenting as pseudopolyps on colonoscopy.

Case Description/Methods: A 50 year old Hispanic female with an incidental finding of microcytic anemia referred to gastroenterology for diagnostic colonoscopy. Physical exam and vitals noncontributory. Blood work notable for Hemoglobin 10.7 g/dL, Hematocrit 36%, MCV 79.3 fl, and a Fecal Calprotectin 56 ug/g. Colonoscopy revealed diffuse moderate inflammation and pseudopolyps in the cecum (Figure 1A), with no ileitis (Figure 1B). Biopsies revealed active chronic colitis with ulceration, concerning for IBD, but found to have organisms consistent with E. histolytica. Treated with a 14 day course of metronidazole. Subsequent stool ova and parasite test was negative. Follow-up blood work notable for Hemoglobin 14.3 g/dL, Hematocrit 43.6 %, and MCV 86.7 fl.

Discussion: Prolonged infection with E. histolytica can mimic chronic colonic inflammation that is seen in IBD. There is a wide differential for precipitants of pseudopolyps outside of E. histolytica. Most commonly seen in IBD with increased prevalence in Ulcerative Colitis, where the left colon is most affected. Other causes include Strongyloides stercoralis, Schistosomiasis, intestinal tuberculosis, and disseminated gastrointestinal histoplasmosis. Features favoring amebic colitis include inflammation involving cecum/right colon without involvement of the terminal ileum, with or without involvement of the rectum. In majority of the cases of amebic colitis, terminal ileum (TI), transverse colon and descending colon will be uninvolved. Discrete ulcers or erosions with normal intervening mucosa in the cecum, non-transmural inflammation, and lack of TI inflammation will help differentiate it from Crohn’s Disease.

In developed countries where the index of suspicion for amoebic colitis is usually low, it is important to consider amoebic colitis especially with atypical presentation of asymptomatic anemia and histological features not consistent with IBD. Misdiagnosis of amoebic colitis as IBD with resultant fulminant colitis from mesalamine/steroids is known to be catastrophic.



Disclosures:


Nirali Sheth, DO¹, Vennis Lourdusamy, MD¹, Ahmed Al-Khazraji, MD², Bhanu Singh, MD¹, Joshua Aron, MD², Raghav Bansal, MD, FACG², Aaron Walfish, MD¹. P2255 - Occult Presentation of Amebic Colitis, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.