Intrahepatic cholangiocarcinoma and encephalomalacia in a budgerigar (Melopsittacus undulatus)

Encephalomalacia is softening or loss of brain tissue following cerebral infarction; cerebral ischemia infection, craniocerebral trauma or other injuries. Cholangiocarcinomas are malignant neoplasms of biliary epithelium, which usually arise from the intrahepatic ducts. A budgerigar was presented with a history of ataxia, decreased activity, neck weakness and weight loss. Supportive care was attempted, but the bird did not improve and euthanasia was elected. At necropsy, the liver was pale and large. There were two symmetrical pale areas on the cortical surface of cerebrum. Representative specimens from all tissues were fixed in 10% buffered formalin, embedded in paraffin and stained with hematoxylin and eosin (HE). In gray matter of cerebral tissue, there were small clear vacuoles of varied size that formed in the cytoplasm of neuron cell bodies. Proliferation of capillaries was seen. The fluid-filled clear spaces were in the white matter especially in peduncles. There were a few thromboses in the vessels and neuronal necrosis of cerebrum. Neoplastic tissue was limited to the liver. There were numerous epithelial lined ducts with an associated dense fibrous stroma. Cholangiocarcinoma and encephalomalacia were confirmed based on the macroscopic and microscopic evidences. It seems that chronic exposure to a mycotoxin and vitamin E deficiency are probable causes of encephalpmalacia and cholangiocarcinoma in this bird.