IntroductionHepatopulmonary syndrome is a rare disease that affects patients of any age with acute or chronic liver disease. Liver transplantation is the only therapeutic option of proved benefit, and can result in substantial improvement or total improvement in postoperative gas exchange abnormalities.Case presentationWe report the case of a cyanotic 13-year-old Pakistani boy whose chest computed tomography scan showed normal lung fields and mediastinum with incidental findings of a prominent liver surface with a collateral vein connecting a portal cavernoma to the dilated terminal inferior vena cava. Sonography of his abdomen along with a portal venous Doppler study showed multiple collateral veins replacing the portal vein. A liver biopsy revealed congenital hepatic fibrosis. Contrast-enhanced echocardiography with agitated saline and a 99m Technetium-macroaggregated albumin perfusion lung scan confirmed intrapulmonary shunting. The patient underwent a successful liver transplantation that resulted in improved gas exchange.ConclusionsHepatopulmonary syndrome should be included in the differential diagnosis of unexplained hypoxemia with an evaluation of possible portal hypertension or liver disease even in the absence of other clinical symptoms.