S5748 Porto-Sinusoidal Vascular Disorder: A Case Report and Diagnostic Challenge

Introduction: Porto-sinusoidal vascular disorder (PSVD), previously termed idiopathic non-cirrhotic portal hypertension, is a rare and under-recognized vascular liver disease marked by signs of portal hypertension without cirrhosis or portal vein thrombosis. Histologically, PSVD includes patterns such as obliterative portal venopathy, nodular regenerative hyperplasia, or incomplete septal fibrosis, often requiring expert pathologic review. Though frequently asymptomatic, PSVD may present with complications like varices, ascites, or splenomegaly. Diagnosis involves exclusion of other liver diseases and confirmation of characteristic histology. It can be idiopathic or secondary to immune-mediated disorders, infections, medications, or prothrombotic states. Case Description/Methods: A 51-year-old man with no medical history presented for evaluation of elevated liver enzymes. Labs showed alanine aminotransferase 127, aspartate aminotransferase 102, alkaline phosphatase 775, and total bilirubin 0.7. Ultrasound revealed a 1.4 cm hyperechoic lesion in the left hepatic lobe; MRI showed a small arterial-enhancing lesion without delayed enhancement, favoring hemangioma. Workup for viral, autoimmune, genetic, and toxic etiologies was unremarkable. MR/MRCP showed heterogeneous hyperenhancement with early washout, peripheral reticulation, mild periportal edema, and perihepatic ascites, with patent hepatic and portal vasculature—findings concerning for sinusoidal obstruction syndrome. Liver biopsy revealed pan-zonal hepatocyte atrophy, sinusoidal expansion, hyalinization of central veins and portal tracts, and fibrous portal tract expansion, without cholestasis, steatosis, necrosis, neoplasia, or inflammation. Discussion: This case highlights the diagnostic challenge of PSVD, particularly in patients without typical risk factors. Despite preserved liver function and patent vasculature, subtle imaging findings and compatible histology supported the diagnosis. Early recognition is key to anticipating complications such as variceal bleeding and avoiding misdiagnosis as cirrhosis. Though liver stiffness is often low in PSVD, recent data suggest spleen stiffness ≤40 kPa with bilirubin <1.0 mg/dL may help exclude high-risk varices and reduce screening endoscopies. This case emphasizes the importance of integrating imaging, pathology, and clinical context to diagnose PSVD early and accurately.