Histological features in western patients with idiopathic non‐cirrhotic portal hypertension

Aims In the western world, idiopathic non‐cirrhotic portal hypertension ( INCPH ) is a rare disease. This study aimed to investigate the histopathological features in western INCPH patients and to assess pathological differences between liver specimens of INCPH with and without HIV . Methods and results Biopsies of 70 INCPH patients (of which 15 were HIV ‐infected) were compared to 23 patients with non‐cirrhotic portal vein thrombosis ( PVT ), which served as a control group for non‐cirrhotic portal hypertension. Phlebosclerosis, nodular regeneration ( NR ), sinusoidal dilatation, paraportal shunting vessels, perisinusoidal fibrosis and portal tract remnants were the most prevalent morphological features of INCPH . There were significant ( P  <   0.01) morphological differences between INCPH and PVT liver specimens with regard to portal tract remnants (46% versus 0%), phlebosclerosis (95% versus 65%), portal vein dilatation (34% versus 78%) and NR (56% versus 22%). The degree of NR correlated with the severity of phlebosclerosis ( P  <   0.01). NR was seen more frequently in the HIV – INCPH group, compared to the non‐ HIV ‐infected patients ( P  <   0.001). Conclusion Portal tract remnants, phlebosclerosis and nodular regeneration are typical features of INCPH . Sinusoidal dilatation, paraportal shunting vessels and increased portal and parenchymal vessels might represent pressure‐related morphological signs of portal hypertension. Finally, more nodular regeneration was observed in HIV ‐associated INCPH .