Caecal Ameboma, colorectal malignancy mimicker in young male with ANCA-associated vasculitis

Ameboma refers to the rare development of an inflammatory, ulcerated, exophytic mass in the gastrointestinal tract that can resemble carcinoma. Typically it presents as a right lower quadrant abdominal mass, Patients may also present with diarrhea or constipation and associated systemic symptoms, including weight loss and fever. In this article we present a young man with a background of ANCA associated vasculitis, who presented with fresh lower gastrointestinal bleeding during hospital admission for severe covid-19 pneumonia which turned out to be caecal aemboma. This case is highlighted for its rarity, the diagnostic challenge, and for the major role of colonoscopy as a diagnostic tool for this pathology.

Ameboma: a colon carcinoma-like lesion in a colonoscopy finding

Ameboma is a rare complication of amebic colitis presenting as a mass of granulation tissue with peripheral fibrosis and a core of inflammation related to amebic chronic infection. The initial presentations are usually obstruction and low gastrointestinal bleeding. The most common sites are the ascending colon and the cecum. It may mimic colon carcinoma, Crohn's disease, carcinoma of the colon, non-Hodgkin's lymphoma, tuberculosis, fungal infection, AIDS-associated lymphoma and Kaposi's sarcoma in colonoscopy findings. The therapeutic strategy should be combined with antibiotics for invasive dysentery and eradication of luminal cysts.

Invasive amebiasis and ameboma formation presenting as a rectal mass: An uncommon case of malignant masquerade at a western medical center

A 54-year-old man presented with rectal pain and bleeding secondary to ulcerated, necrotic rectal and cecal masses that resembled colorectal carcinoma upon colonoscopy. These masses were later determined to be benign amebomas caused by invasive Entamoeba histolytica, which regressed completely with medical therapy. In Western countries, the occurrence of invasive protozoan infection with formation of amebomas is very rare and can mistakenly masquerade as a neoplasm. Not surprisingly, there have been very few cases reported of this clinical entity within the United States. Moreover, we report a patient that had an extremely rare occurrence of two synchronous lesions, one involving the rectum and the other situated in the cecum. We review the current literature on the pathogenesis of invasive E. histolytica infection and ameboma formation, as well as management of this rare disease entity at a western medical center.

Ileocecal masses in patients with amebic liver abscess: Etiology and management

AIM: To assess the causes of ileocecal mass in patients with amebic liver abscess.

METHODS: Patients with amebic liver abscess and ileocecal mass were carefully examined and investigated by contrast-enhanced CT scan followed by colonoscopy and histological examination of biopsy materials from lesions during colonoscopy.

RESULTS: Ileocecal masses were found in seventeen patients with amebic liver abscess. The cause of the mass was ameboma in 14 patients, cecal tuberculosis in 2 patients and adenocarcinoma of the cecum in 1 patient. Colonic ulcers were noted in five of the six (83%) patients with active diarrhea at presentation. The ileocecal mass in all these patients was ameboma. Ulcers were seen in only one of the 11 (9%) patients without diarrhea. The difference was statistically significant from the group with diarrhea (P < 0.005).

CONCLUSION: Ileocecal mass is not an uncommon finding in patients with amebic liver abscess. Although, the ileocecal mass is due to ameboma formation in most cases, it should not be assumed that this is the case in all patients. Colonoscopy and histological examination of the target biopsies are mandatory to avoid missing a more sinister lesion.