Intrathoracic ectopic liver in a cow.

A solitary spherical mass was found in the caudal part of the cranial lobe of the left lung of a 28-month-old Japanese Black cow. The mass was circumscribed, embedded in the lung parenchyma and not connected to the liver or diaphragm. Histologically, the mass comprised hepatocytes, portal structures consisting of interlobular bile ducts, interlobular arteries and interlobular veins, and central veins. Based on the histological findings, a diagnosis of intrathoracic ectopic liver was made. Considering the absence of any previous history of traumatic diaphragmatic hernia or surgery, the mass might have resulted from a congenital abnormality. To our knowledge, this is the first report of intrathoracic ectopic liver in a cow that might have resulted from a congenital abnormality.