Type Ib Abernethy Malformation Complicated by Hepatopulmonary Syndrome: A Case Report of a Rare Entity in a Pediatric Patient

Abernethy malformation is a rare congenital extrahepatic portosystemic shunt (CEPSh) characterized by the diversion of portal venous blood away from the liver into the systemic circulation, resulting in a wide spectrum of hepatic, pulmonary, and systemic complications. Hepatopulmonary syndrome is an important but uncommon association that results from intrapulmonary vascular dilatation secondary to portosystemic shunting. We describe the case of a two-year-old female who was evaluated for recurrent respiratory tract infections, cyanosis, and digital clubbing. Radiologic assessment demonstrated a Type Ib Abernethy malformation characterized by the formation of a common spleno-mesenteric trunk draining directly into the inferior vena cava, complete diversion of portal venous flow, and the absence of intrahepatic portal venous radicals. CT pulmonary angiography further revealed dilated distal pulmonary vasculature compatible with hepatopulmonary syndrome. Prompt radiologic recognition of this rare vascular anomaly is crucial, particularly when pulmonary manifestations are present, as timely diagnosis and referral for definitive management, including liver transplantation, can significantly improve clinical outcomes.