Obliterative portal venopathy: a clinical and histopathological review

Non-cirrhotic portal hypertension (NCPH) is characterized by the elevation of the portal pressure in the absence of cirrhosis. Obliterative portal venopathy (OPV) as a cause of NCPH is being increasingly diagnosed, especially after recent reports of its occurrence in patients with HIV using didanosine. Patients usually present with episodes of variceal hemorrhage and other features of portal hypertension including jaundice, ascites, encephalopathy and hepatopulmonary syndrome. Hepatic synthetic function is typically well preserved and the laboratory evaluation in OPV patients typically reveals only mild nonspecific hematological abnormalities chiefly related to hypersplenism. Its diagnosis remains a challenge and patients are often mistakenly diagnosed as having cirrhosis. Despite the increasing recognition of OPV, its etiology and pathogenesis are still unclear. A number of etiologies have been proposed including genetic predisposition, recurrent bacterial infections, HIV infection and highly active antiretroviral therapy, an altered immune response, hypercoagulability, and exposure to chemicals and certain medications. Histopathological evaluation remains critical in excluding cirrhosis and other causes of portal hypertension, and is the only way of definitively establishing the diagnosis of OPV. Clinicians should have a high index of suspicion for OPV in patients who present with variceal bleeding and splenomegaly and who do not have other features of cirrhosis. The purpose of this review is to summarize the known etiologies for OPV and its associated clinical aspects and correlations, and to also provide ample histophotomicrographs of OPV to aid in the diagnosis. It will also help raise awareness of this entity amongst pathologists and clinicians alike.