Porto-Sinusoidal Vascular Disease and Focal Nodular Hyperplasia-like Nodules in a Patient with Neurofibromatosis and Non-Cirrhotic Portal Hypertension

Introduction/Objective Non-cirrhotic portal hypertension (NCPH) is uncommon. The underlying pathophysiology appears to lie at the level of intrahepatic portal veins and sinusoids, hence the term “porto-sinusoidal vascular disease” (PSVD). We report a rare case of PSVD with focal nodular hyperplasia (FNH)-like nodules in a patient with neurofibromatosis type 2 (NF2). Methods/Case Report A 57-year-old male with NF2 and type 2 diabetes, presented with a large variceal bleed requiring blood transfusion and subsequent transjugular intrahepatic portosystemic shunt (TIPS). Imaging showed a nodular liver, presumed to be cirrhosis due to non-alcoholic liver disease. Liver biopsy was not done. Thereafter, he had several episodes of hepatic encephalopathy and TIPS was downsized to prevent recurrences. The patient required liver transplantation for intractable portal hypertension and severe hepatic encephalopathy; his liver synthetic function was near normal and MELD was 11. Portal vein was patent. The explanted liver was micronodular, soft and weighed 946 grams. Unencapsulated nodules, a few mm to 1 cm in size, were present. Microscopically, there was diffuse nodularity in the absence of bridging fibrosis. Thin, incomplete curvilinear fibrous septa were present. There were aberrant veins, hypervascular portal tracts, herniated portal veins and rare occluded portal veins. Trichrome and reticulin stains confirmed architectural abnormalities including nodularity, lack of bridging fibrosis and approximation of portal tracts. Immunohistochemistry for glutamine synthetase accentuated architectural distortion and revealed nodules with FNH-like geographic areas of staining. Results (if a Case Study enter NA) NA Conclusion This is a rare case of NCPH due to PSVD in a patient with NF2. Microscopy suggested incomplete septal cirrhosis (ISC), a pattern associated with both PSVD and regression of fibrosis in a cirrhotic liver. Isolated portal hypertension without loss of synthetic function favors primary PSVD over regression of fibrosis. FNH-like nodules are consistent with regenerative changes caused by localized abnormalities of blood flow.