An Exceptional Rarity: Coexisting Amebic Enterocolitis and Metastatic Colon Adenocarcinoma Deceptively Resembling Crohn's Disease Grossly

Abstract

Abstract Introduction/Objective Amebiasis is a parasitic infection that is rare in developed countries but mimic crohn’s disease or colon malignancy. Amoeboma of the large intestine, a subtype of amebiasis, is an even rarer condition that can be challenging to differentiate from colorectal carcinoma. While co-occurrence of these two conditions is exceedingly rare, we present a unique case of severe fulminant necrotizing colitis with perforation, which coexisted with metastatic colon adenocarcinoma. Methods/Case Report A 54-year-old female with no travel history, recently diagnosed with sigmoid colon cancer and liver metastasis, presented with acute worsening of her chronic abdominal pain. Upon examination, a sigmoid/rectal mass with local invasion of the bladder and left salpinx, along with liver metastases, was discovered. The patient underwent an emergent exploratory laparotomy, total abdominal colectomy, and end ileostomy due to concerns for perforation. The colon's mucosa displayed a cobblestone-like appearance with diffusely raised tan areas, erosions, exudate, and intervening brown mucosa (Figure 1). Microscopic examination revealed amebic trophozoites invading submucosa diffusely with ingested RBCs in cytoplasm, small round nucleus with dot-like karyosome (figure 2), involving the colon and attached terminal ileum, with perforations in the terminal ileum and ascending colon. The trophozoites were further confirmed by negative CD68 stain, and strongly PAS stain. Additionally, metastatic adenocarcinoma (figure 3-5) was found in two lymph nodes, along with tumor deposits in the mesenteric fat, but no primary adenocarcinoma was identified despite extensive search and sampling. Postoperatively, the patient completed an antibiotic course for Entamoeba, with a smaller lesion near the gallbladder responded, the hepatic lesion remained unchanged, indicating metastatic disease. Results (if a Case Study enter NA) NA Conclusion Although the colectomy specimen's gross findinds initially suggested Crohn's disease, the overall microscopic features favored amebic colitis due to the presence of numerous amebic trophozoites and the patient's lack of IBD history.This case highlights the potential coexistence of colonic amebiasis and colorectal carcinoma, which can mimic each other. This case serves as a reminder to avoid delayed diagnosis and treatment of ameboma infection in patients with colon malignancy history, even in non-endemic countries like the United States. .