Solitary Cecal Ulcer Presenting as Amebic Colitis

Abstract

Purpose: A 24 y/o Polish male presented w/ diarrhea that was occasionally bloody and mixed w/ mucous for the past few weeks. Pt admitted to a 20 lb unintentional weight loss. He denied recent travel, sick contacts, or antibiotic use. The diarrhea was associated with crampy lower abdominal pain and tenesmus. Physical exam was completely normal. He was afebrile and CBC was within normal limits. Stool studies were negative for infection. The patient's family history was significant for Crohn's disease in his father. A colonoscopy was performed to the terminal ileum where a single cecal ulcer was visualized, and the remainder of the cecal mucosa was friable. The rest of the colonic as well as terminal ileal mucosa were normal. Biopsies taken from the ulcer margin were consistent w/ amebic colitis - E. histolytica. The patient was treated with metronidazole with good resolution of his symptoms. Dysentery has been documented to account for more than 90% of cases of invasive intestinal amebiasis, but is mainly seen in poor socioeconomic areas and rare in U.S. However, tissue invasion can occur leading to amebic colitis. It may be associated with other conditions including: ulcerative colitis, toxic megacolon, or amebic appendicitis. It may occur months to years after exposure so it's important to keep in mind as a differential diagnosis. Chronic intestinal amebiasis has also been described and may last for months to years with chronic abdominal pain, weight loss, and diarrhea. Typical intestinal amebic ulcers (“flask shaped”) are found in the cecum, sigmoid, and rectum and may be nodular or irregular. Irregular ulcers 1 to 5 cm are usually found in the cecum and are shallow with fibrin filled centers. However, most case reports describe presentation ranging from multiple ulcers to diffuse ulceration and hemorrhage. The pathogenesis of the ulcer has been described in 3 stages where the trophozoites are able to lyse the colonic mucosa, allowing the parasite to attach and cause further degradation of the extracellular matrix. However, studies are currently ongoing to fully understand the sequence of events during amebic invasion of the colon.Figure