Porto-sinusoidal Vascular Disease: Classification and Clinical Relevance

Abstract

Non-cirrhotic portal hypertension (NCPH) is a well-recognized clinico-pathological entity, which is associated with clinical signs and symptoms, imaging, and endoscopic features of portal hypertension (PHT), in absence of cirrhosis. In patients with NCPH without known risk factors of portal hypertension or extrahepatic portal vein thrombosis, the condition is called idiopathic NCPH or INCPH. There are multiple infectious, immune related causes, systemic diseases, drug and toxin exposures, haematological disorders, and metabolic risk factors that have been associated with this INCPH. However, the causal pathogenesis is still unclear. The VALDIG group recently proposed porto-sinusoidal vascular disease (PSVD) as a syndromic entity, which provides definite histopathological criteria for diagnosis of noncirrhotic portal hypertension. (Table 1) The three classical histo-morphological lesions specific for PSVD include obliterative portal venopathy (OPV), nodular regenerative hyperplasia (NRH) and incomplete septal fibrosis. The PSVD definition includes patients with portal vein thrombosis, PVT and even those without PHT, thus broadening the scope of diagnosis to include patients who may have presented early, prior to hemodynamic changes consistent with PHT. However, this new diagnosis has pros and cons. The cons include mandating invasive liver biopsy to assess the PSVD histological triad in ALL patients with NCPH, an erstwhile clinical diagnosis in Asian patients. In addition, the natural history of the subclinical forms of PSVD without PHT and linear progression to develop PHT is unknown yet. In this review, we discuss the diagnosis and treatment of INCPH/PSVD, fallacies and strengths of the old and new schema, pathobiology of this disease and clinical correlates, in an Asian context. Although formulation of standardised diagnostic criteria is useful for comparison of clinical cohorts with INCPH/PSVD, prospective clinical validation in global cohorts is necessary to avoid misclassification of vascular disorders of the liver.