S5786 Unmasking a Hidden Parasite: Colonic Necrosis and Liver Abscess From Entamoeba histolytica

Introduction: Entamoeba histolytica (EH) is a parasitic protozoan transmitted via the fecal-oral route, with amebic liver abscess as its most common extraintestinal manifestation. We present a rare case of a perforated EH liver abscess. Case Description/Methods: A 63-year-old man with hypertension and recent travel to Mexico presented with an 8-day history of fever, diarrhea, and worsening diffuse abdominal pain. Initial computed tomography (CT)of the abdomen and pelvis (A/P) revealed mass-like thickening from the ascending to proximal transverse colon, involving the appendix. The liver appeared normal without focal lesions. Despite bowel rest and empiric broad-spectrum antibiotics, there was no clinical improvement. The patient underwent a right hemicolectomy with end ileostomy. On postoperative day 2, he remained tachycardic with worsening leukocytosis. Repeat CT A/P showed new multiple bi-lobar hepatic abscesses (1–3 cm) and a large peri-colonic abscess (14.5 × 6.9 × 9.8 cm) in the right colon bed. Infectious Disease and Interventional Radiology were consulted. Intravenous unasyn and flagyl were initiated, and a CT-guided drain was placed into the peri-colonic abscess. Histopathology of the resected colon specimen confirmed Entamoeba histolytica as the causative organism, leading to colonic necrosis. The patient improved with therapy. Prior to discharge, the peri-colonic drain was removed. He was discharged to a skilled nursing facility with a PICC line for intravenous Unasyn and oral metronidazole and paromomycin. Discussion: Entamoeba histolytica infection ranges from asymptomatic colonization to life-threatening complications such as amebic liver abscess, intestinal perforation, and sepsis. Our case highlights an unusual presentation of EH with colonic involvement and delayed development of hepatic abscesses following colonic perforation. This emphasizes the need to consider EH in patients with compatible symptoms and travel history to endemic areas. Prompt diagnosis and a multidisciplinary approach - encompassing infectious disease, radiology, and surgery - are crucial to reduce morbidity and mortality. Awareness of such rare presentations is essential for timely management and to prevent further complications.