Porto-sinusoidal vascular disorder.

It is well established that portal hypertension (PH) can occur in the absence of cirrhosis, as reported in patients with immune disorders, infections and thrombophilia. However, similar histological abnormalities affecting primarly the hepatic sinusoidal and the (peri)portal vasculature have also been observed in patients without PH. Thus, the term porto-sinusoidal vascular disorder (PSVD) has been recently introduced to describe a group of vascular diseases of the liver featuring lesions encompassing the portal venules and sinusoids, irrespective of the absence or presence of portal hypertension. Liver biopsy is fundamental for PSVD diagnosis. Specific histology findings include nodular regenerative hyperplasia, obliterative portal venopathy/portal vein stenosis and incomplete septal fibrosis/cirrhosis. Since other conditions including alcoholic and non-alcoholic fatty liver disease, or viral hepatitis, or the presence of portal vein thrombosis may occur in patients with PSVD, their relative contribution to the liver damage should be carefully assessed. In addition to histology and clinical diagnostic criteria, imaging and noninvasive tests such as liver and spleen stiffness measurements seem to aid in the diagnostic workup. The introduction of PSVD as a novel clinical entity will facilitate collaborative studies and investigations of the underlying molecular pathomechanisms.