Combined hepatocellular-cholangiocarcinoma in a Yellow-headed Amazon (Amazona oratrix).

A 9-year-old male Yellow-headed Amazon (Amazona oratrix) with a history of anorexia and vomiting died of a liver tumor. The tumor consisted of neoplastic cells with hepatocellular and cholangiocellular differentiations and their intermingled areas. Neoplastic hepatocytes showed islands or trabecular growth with vacuolated eosinophilic cytoplasm. Cells showing biliary differentiation formed ducts or tubules lined by cytokeratin AE1/AE3-positive epithelia, accompanied by desmoplasia consisting of myofibroblasts reacting to alpha-smooth muscle actin and desmin. The tumor was diagnosed as a combined hepatocellular-cholangiocarcinoma, which is very rare in the avian.