Ruptured hepatocellular carcinoma developed in a normal liver in a young patient with a body mass index of 33 kg/m2.

Hepatocellular carcinoma (HCC) in young patients is rare, and the most common cause is hepatitis B viral infection. We report a case of ruptured HCC in a man in his 30s with a body mass index of 33 kg/m² without hepatitis viral infection. He had multiple HCC with distant metastases at the first visit. On the 6th day after admission, he underwent transcatheter arterial embolisation for HCC rupture, but died the following day. Pathological autopsy revealed moderately to poorly differentiated HCC without evidence of fibrolamellar carcinoma, which is common in young patients with HCC. Based on his history of obesity and fatty liver, we presumed that he had metabolic dysfunction-associated steatohepatitis. However, his non-neoplastic liver was normal. The HCC might have developed from metabolic dysfunction-associated steatotic liver disease, followed by regression of the underlying hepatic steatosis as the patient lost weight owing to HCC progression.