Colon, Amebiasis [LMP13277]

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Diagnostic Modality: 
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Disease Category: 
Infectious Diseases
Diagnosis: 
Amebiasis
Species: 
Human
Organ System: 
Gastrointestinal Tract
Gender: 
Male
Age: 
45 years
Diagnosis Code: 
ICD-10: A06.1
Slide Contributor Information
Kirsch, R., Nanji, S., Chang, M.

Keywords

amoeba, amoebiasis, entamoeba

Clinical History

Patient presenting with bloody diarrhea. Sections of colonic tissue were examined.

Clinical Discussion

Amebiasis is a parasitic infection most commonly caused by the protozoan Entameba histolytica. It is prevalent in tropical regions and is transmitted through fecal-oral route. It can cause a range of symptoms from no symptom/mild dysentery to fulminant colitis. The cecum is most commonly affected. It causes flask-shaped ulcers and may mimic chronic idiopathic inflammatory bowel disease.

Ameba trophozoites have foamy cytoplasm with round eccentrically located nuclei and are usually found in ulcer base or adherent inflammatory exudate. Ingested red blood cells might be found in the cytoplasm which differentiates it from non-pathogenic strains. The trophozoite might be mistaken with macrophages which have larger, more irregular and hyperchromatic nuclei. PAS and CD68 stains are helpful to differentiate ameba trophozoites (PAS positive, CD68 negative) from macrophages (PAS negative, CD68 positive).