JPC SYSTEMIC PATHOLOGY
DIGESTIVE
September 2018
D-P04

SIGNALMENT (JPC #2317402):  African green monkey (Cercopithecus aethiops)

HISTORY:  Incidental finding at necropsy

HISTOPATHOLOGIC DESCRIPTION:  Liver: Multifocally and randomly affecting approximately 15% of the hepatic parenchyma are scattered, variably sized, up to 4mm, granulomas characterized by a central area of eosinophilic cellular and karyorrhectic debris (lytic necrosis) admixed with abundant degenerate eosinophils and neutrophils, basophilic material (mineral), surrounded by moderate numbers of epithelioid macrophages, eosinophils and few multinucleated giant cells, further surrounded by plasma cells, lymphocytes, few fibroblasts and minimal fibrous connective tissue. Adjacent hepatocytes are frequently pale with swollen cytoplasm (degenerate), or, less commonly, shrunken with hypereosinophilic cytoplasm and pyknosis (necrotic). Multifocally associated with granulomas or randomly scattered within the parenchyma there are round to oval protozoal merocysts ranging from 300-1800 um in diameter with a thin eosinophilic hyaline capsule and containing numerous oval to elongate to irregular 25X50um schizonts, which have a 2um eosinophilic capsule imparting a internally septate appearance to the merocyts, and are filled with abundant 2-3 um basophilic merozoites. Larger, more mature merocysts undergoing various stages of degeneration or rupture, have a large central cavitation with fibrillar eosinophilic material and a basophilic merozoites scattered througout. There are low numbers of portal/periportal lymphocytes and plasma cells as well as scattered macrophages and hepatocytes which contain brown granular pigment (hemosiderin).

MORPHOLOGIC DIAGNOSIS:  Liver: Granulomas, eosinophilic, multiple, random, with protozoal merocysts, etiology consistent with Hepatocystis kochi, African green monkey (Cercopithecus aethiops), nonhuman primate.

ETIOLOGIC DIAGNOSIS:  Hepatic hepatocystosis

CAUSE:  Hepatocystis kochi

GENERAL DISCUSSION:

PATHOGENESIS:

LIFE CYCLE: 

TYPICAL CLINICAL FINDINGS: 

TYPICAL GROSS FINDINGS: 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Benirschke K, Farner F, Jones T. Protozoal and metazoal diseases. In: Pathology of Laboratory Animals. New York, NY: Springer-Verlag; 1978:1612.
  2. Flynn R. Sporozoans and neosporans. In: Parasites of Laboratory Animals. Ames, IA: The Iowa State Univeristy Press; 1973:72-5.
  3. Gardiner C, Fayer R, Dubey J. An Atlas of Protozoan Parasites in Animal Tissues. Washington, DC: American Registry of Pathology; 1998:67-8.
  4. Strait K, Else JG, Eberhard ML. Parasitic diseases of nonhuman primates. In: Abee CR, Mansfield K, Tardif S, Morris T, eds. Nonhuman Primates in Biomedical Research: Diseases. Vol 2. San Diego, CA: Academic Press; 2012:216-218.


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