– Men having sex with men have higher incidence than general population
• Liver abscess is most frequent complication of invasive amebiasis
Clinical Issues
• Fever, sweats, and right upper quadrant pain
• Hepatomegaly, abdominal tenderness
• Elevated alkaline phosphatase, leukocytosis common
• Lab tests
Serologic studies, PCR, stool examination
– Stool exam cannot distinguish between E. histolytica and nonpathogenic ameba
• Treatment
Amebicides
Guided percutaneous drainage may be required for liver abscess
Macroscopic
• Solitary or multiple lesions, often irregularly shaped, ranging from barely visible to > 20 cm
Usually right lobe
Often contain necrosis resembling anchovy paste
Microscopic
• Abundant nuclear debris but few intact inflammatory cells
• Organisms have foamy cytoplasm; round, eccentric nuclei
Ingested red blood cells essentially pathognomonic of E. histolytica
• Trophozoites may mimic macrophages
CT Scan A contrast-enhanced CT of the liver shows an amebic abscess with a surrounding rim . This cavity was filled with thick, tenacious necrotic debris (anchovy paste).
Amebic Liver Abscess Entamoeba histolytica with associated fibrous tissue is shown, but relatively few mononuclear cells are seen at the edge of a liver abscess. Note the residual liver at the bottom 1/2 of the image. (Courtesy Dr. J.C. Garces.)
Ingested Erythrocytes Ingested red blood cells within the organisms are virtually pathognomonic of E. histolytica . A sparse mononuclear cell infiltrate is also present.
Features of Organism High-power view of amebic trophozoites shows the distinct cell membrane, foamy cytoplasm, and round, eccentric nucleus with open chromatin pattern.
TERMINOLOGY
Synonyms
• Entamoeba histolytica; amebiasis ; entamebiasis
Definitions
• Infection of liver by protozoa E. histolytica
Humans are only known reservoir
ETIOLOGY/PATHOGENESIS
Environmental Exposure
• Poor sanitation, exposure to contaminated water
Most common in poor communities with inadequate sanitation
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. This cavity was filled with thick, tenacious necrotic debris (anchovy paste).
with associated fibrous tissue is shown, but relatively few mononuclear cells are seen at the edge of a liver abscess. Note the residual liver at the bottom 1/2 of the image. (Courtesy Dr. J.C. Garces.)
. A sparse mononuclear cell infiltrate is also present.
