AIMS/BACKGROUND: Most cases of hepatocellular carcinoma (HCC) develop in the setting of chronic liver disease (CLD), usually with chronic inflammation, fibrosis, or cirrhosis. The case aims to highlight a rare presentation without evidence of prior CLD. CASE PRESENTATION: An older adult patient with no risk factors for CLD other than type 2 diabetes, overweight, and hypertension presented with high-gradient ascites, splenomegaly and hypersplenism due to portal hypertension. RESULTS: Imaging identified an extensive tumour thrombus extending from the portal vein and hepatic veins to the inferior vena cava and right atrium-adjacent to a liver mass. Alpha-fetoprotein was extremely elevated. Ultrasound-guided core liver needle biopsy of the mass was diagnostic of HCC. Biosynthetic liver functions were preserved, liver imaging did not show cirrhosis or steatosis, and liver tissue adjacent to the tumour showed no CLD. CONCLUSION: HCC may rarely present with tumour thrombus-associated portal hypertension and ascites, and very rarely arise with no demonstrable background of liver pathology. Absence of demonstrable CLD does not rule out HCC and its complications.