Unusual Discovery after an Examination for Abdominal Pain: Abernethy 1b Malformation and Liver Adenomatosis. A Case Report.

Congenital extrahepatic portosystemic shunt (Abernethy malformation) is a rare condition characterized by developmental abnormalities of the portal venous system resulting in the diversion of the portal blood from the liver to the systemic venous system through a complete or partial shunt of the portomesenteric blood. We report the case of an 18 year-old female examined for abdominal pain, presenting cholestasis syndrome and an elevated serum aspartate aminotransferase level. Liver ultrasound examination revealed the absence of the portal vein with a complete extrahepatic shunt of the portal blood, multiple focal liver lesions, and multiple associated vascular anomalies. A surgical portosystemic shunt and a secondary portosystemic shunt due to portal vein thrombosis were excluded, enabling the diagnosis of a congenital portosystemic shunt. A complex investigation also discovered bone anomalies, and the liver biopsy of the dominant focal lesion revealed adenoma. On a short-term follow-up under hepatoprotective medication, the biochemical parameters improved mildly; however, the size of the main focal lesion increased. Congenital absence of the portal vein often remains an incidental diagnosis. In experienced hands, ultrasonography can diagnose it, but a comprehensive thoraco-abdominal evaluation is compulsory, considering the many potential associated anomalies. In these patients, development of adenomatous liver lesions secondary to Abernethy type Ib malformation represents an indication for liver transplantation.