Type II Abernethy Malformation: A Rare Cause of Hepatic Encephalopathy in Adulthood

Abstract

Abernethy malformation is a rare congenital extrahepatic portosystemic shunt with variable clinical manifestations, mainly associated with the portosystemic shunt. Hepatic encephalopathy can be the first manifestation. We present the case of a 50-year-old woman with hepatic encephalopathy without liver dysfunction. Further evaluation with contrast-enhanced abdominal computed tomography was performed, showing a large-calibre portocaval shunt from the left portal branch, suggestive of type 2 Abernethy malformation. The patient improved with lactulose and rifaximin but maintained rare encephalopathy episodes. She is therefore currently awaiting surgical treatment. Despite being a rare cause of hepatic encephalopathy, Abernethy malformation should be considered in patients with unexplained hyperammonaemia. Since it is potentially reversible, and early diagnosis and treatment may improve outcome, raising awareness of this malformation is essential.

Learning points: Abernethy malformation is a rare congenital extrahepatic portosystemic shunt with variable clinical manifestations, some associated with the portosystemic shunt; hepatic encephalopathy can be the first manifestation.Initial recognition of the presence of encephalopathy in non-cirrhotic individuals can be challenging, and patients may have symptoms for a long period of time before being diagnosed.This entity, although rare, should be looked for in patients with hepatic encephalopathy without evidence of liver disease, mainly because it can be submitted to targeted treatment.

Keywords: Abernethy malformation; encephalopathy; hyperammonemia; portosystemic shunt.

Figure 1

Axial (A) and coronal (B) CT images, in portal venous phase, showing a latero-lateral portocaval shunt of the left portal branch (yellow arrows)