Obliterative Portal Venopathy: A Rare Cause of Pre-sinusoidal Portal Hypertension

Abstract

Introduction: Making an etiologic diagnosis in patients with noncirrhotic portal hypertension can often be a formidable challenge for clinicians. We describe a rare case of pre-sinusoidal intrahepatic portal hypertension. Case: A 54-year-old man presented with an upper GI bleed. He had a longstanding history of fibrostenotic Crohn's disease s/p surgical resections and therapy with various immunomodulating agents. He had a history of massive splenomegaly and thrombocytopenia (platelets ˜40,000), for which he'd been followed by a hematologist without a definitive diagnosis, despite numerous tests including a bone marrow biopsy. An EGD revealed large, grade four esophageal varices, for which he underwent several variceal band ligation sessions. Initial CT imaging demonstrated a non-cirrhotic liver with a 25-cm spleen, patent portal, hepatic and splenic veins, and no ascites. LFT's were normal, and an MRCP showed no evidence of PSC. Viral, autoimmune, and genetic etiologies of chronic liver disease were unrevealing. A transjugular liver biopsy revealed a borderline elevated hepatic venous pressure gradient of 8 mmHg. Histology showed moderate macrovesicular steatosis (30%) and a NAFLD activity score (NAS) of 3/8. In addition, there were prominent periportal shunt vessels with muscularization of small portal vein branches and nodular regenerative hyperplasia changes; all consistent with a diagnosis of “obliterative portal venopathy (OPV).” There was mild periportal fibrosis (2/4), but no cirrhosis. A full hypercoaguable work-up failed to reveal an underlying clotting disorder. A partial splenic artery embolization was performed to reduce the spleen volume, prevent recurrent portal hypertensive bleeding, and improve the patient's thrombocytopenia. Several weeks post-procedure, his platelet count rose to the 200,000 range, and there was complete resolution of varices on follow-up EGD. He has since developed evidence of some thrombosis in the splenic and portal veins, requiring anti-coagulation. Discussion: OPV has also been termed “hepatoportal sclerosis,” “noncirrhotic intrahepatic portal hypertension,” and “idiopathic presinusoidal portal hypertension,” a rare etiology of portal hypertension diagnosed by the astute pathologist, based on specific histologic features. There is usually minimal-to-moderate portal fibrosis, but no cirrhosis and a patent splenoportal venous axis. The mechanism of disease pathogenesis is unclear, but in our patient, an autoimmune/inflammatory disease of the gut may predispose to portal bacteremia/pylephlebitis, which may result in thrombosis, sclerosis, and obstruction of small- and medium-sized portal vein radicals. His long-term exposure to 6 MP/imuran is another putative precipitating factor.