October 2018

SIGNALMENT (JPC #2550908):  Adult female Barbary ape (Macaca sylvana)

HISTORY:  This animal was kept in a zoo.

HISTOPATHOLOGIC DESCRIPTION:  Liver: Expanding and replacing approximately 50% of the hepatic parenchyma in this section and compressing adjacent hepatocytes is a multilocular alveolar hydatid cyst composed of round to oval to irregular intact and ruptured 2-6 mm diameter cysts surrounded and separated by variably thick bands of fibrous connective tissue that extend into and replace adjacent hepatic parenchyma. Fibrous connective tissue contains moderate numbers of lymphocytes, plasma cells, macrophages and eosinophils, and many entrapped bile ductules.  Cysts are lined by a 10-50 um thick eosinophilic hyaline outer laminated membrane and a 50-150um inner germinal epithelial layer containing basophilic nuclei, eosinophilic flocculant to granular material, and numerous 5-20 um basophilic calcareous corpuscles. Budding from the germinal epithelium or free within the cyst lumen are many thin-walled brood capsules containing multiple 100-150 um diameter protoscolices. Protoscolices have a 5 um thick tegument enclosing spongy parenchyma which contains calcareous corpuscles, a sucker and a rostellum armed with birefringent hooks. Ruptured cysts are collapsed and contain variable amounts of eosinophilic necrotic debris admixed with degenerate neutrophils, eosinophils, lymphocytes, plasma cells, foamy macrophages and multinucleated giant cells, which extend into the adjacent fibrous connective tissue. Multifocally, throughtout the adjacent hepatic parenchyma, hepatocytes are necrotic with shrunken hypereosinophilic cytoplasm and pyknosis, are individualized and surrounded by hemorrhage, are degenerate, with swollen, pale, vacuolated cytoplasm or are lost and replaced by necrotic debris, hemorrhage and/or fibrosis. Portal areas adjacent to the hydatid cyst and areas of hepatocellular necrosis have increased numbers of small bile duct profiles (biliary ductal reaction).

MORPHOLOGIC DIAGNOSIS:  Liver: Hydatid cyst, multiloculated, with multifocal fibrosis, necrotizing hepatitis and biliary hyperplasia, etiology consistent with Echinococcus multilocularis, Barbary ape (Macaca sylvana), primate.

ETIOLOGIC DIAGNOSIS:  Hepatic echinococcosis

CAUSE:  Echinococcus multilocularis

CONDITION:  Alveolar or multilocular hydatid disease










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Click on image for diagnostic series.

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