Abstract

Amoebic colitis typically presents with abdominal pain and diarrhoea, the vast majority of patients being asymptomatic carriers. Developing countries with poor socioeconomic and sanitation conditions and immigrants from these countries are disproportionately represented. We describe a patient presenting with constipation and abdominal pain who underwent colonoscopy showing caecal ulceration. Histology showed the typical features of amoebic colitis. Our case highlights an unusual presentation of amoebic colitis and its ability to masquerade as other conditions such as Inflammatory Bowel Disease (IBD) or NSAID induced colitis.

Keywords: Amoebic colitis; Entamoeba histolytica; Colonic ulceration; Constipation.

Citation: Clifford C, Manji ZA, Cotter MB, O’Reilly S. Amoebic colitis the great masquerader. J Clin Images Med Case Rep. 2024; 5(8): 3197.

Case description

A 57-year-old man was referred for colonoscopy with a three month history of constipation and right sided abdominal pain. He denied bleeding per rectum, weight loss, fevers or any red flag symptoms. Background medical history was unremarkable with no significant family history or recent foreign travel. He was using Non- Steroidal Anti-Inflammatory Drugs (NSAIDs) regularly over the previous three weeks. On examination there was tenderness in the right inguinal fossa. Laboratory findings, stool cultures and fecal calprotectin were normal. Initial colonoscopy showed discrete ulceration in the cecum (Figure 1). Repeat colonoscopy six months later showed progression of the ulcerated area in the cecum (Figure 2). Symptoms continued despite ceasing NSAIDs. H&E stained sections show typical histological findings described in amoebic colitis with superficial epithelial ulceration and an overlying inflammatory exudate (Figure 3) [1]. Amoebic trophozoites are commonly seen within the inflammatory exudate, described as round pink/ red eosinophilic nuclei and vacuolated pink eosinophilic nuclei and vacuolated pink eosinophilic cytoplasm [1]. Ingested red cells can occasionally be seen within the cytoplasm and are considered diagnostic for the entamoeba histolytica trophozoites (Figure 4) [2]. He was treated with oral metronidazole and permethrin for 10 days with resolution of symptoms.

References

1. Yue B, Meng Y, Zhou Y, et al. Characteristics of endoscopic and pathological findings of amebic colitis. BMC Gastroenterol. 2021; 21: 367.
2. Tanyuksel M, Petri Jr WA. Laboratory diagnosis of amebiasis. Clinical microbiology reviews. 2003; 16(4): 713-29.