Histopathological features of idiopathic portal hypertension: A systematic review and meta-analysis

Background Portal hypertension (PH) is a clinically significant entity that could present with life-threatening gastrointestinal bleeding. Cirrhosis is the most common cause of PH, with well-documented histopathology and etiology. However, in idiopathic portal hypertension (IPH), no single histopathologic finding is associated with PH. Our systematic review aims to identify and summarize the prevalence of the common histological findings of IPH. Methods We systematically searched PubMed, Cochrane CENTRAL, Web of Science, and Scopus till 1ST March 2022 for studies describing the histopathological features of IPH. Data were extracted from eligible studies and pooled as events rate and 95% confidence interval (CI) using binary random-effects model by open meta-analyst software. Results We included 23 retrospective studies with a total sample size of 813 patients. The overall incidence of nodular regenerative hyperplasia was 38.6%, 59.8% for portal fibrosis, 51.3% for periportal fibrosis, 39.3% for perisinusoidal fibrosis, 89.8% for portal vein sclerosis, 42.2% for portal inflammation, 53.3% for mega-sinusoids, 39.5% for thickening of portal vein branches, 93.8% for narrowing of portal veins, 53.3% for hepatic veins/venous outflow obstruction, 51.4% for aberrant portal/periportal vessels, 42.4% for shunt vessel, 50.9% for ductular proliferation, and 16.3% for steatosis. Conclusion Due to the relatively non-pathognomonic and non-specific nature of IPH, a combination of different histological features such as the portal and periportal fibrosis, portal vein sclerosis, mega-sinusoids, narrowing of portal veins, hepatic venous outflow obstruction, aberrant portal or periportal vessels, and ductular proliferation may be of value in diagnosing IPH as the incidence rate of these features was at approximately 50%.