Pathological evidence of the cause of spontaneous regression in a case of resected hepatocellular carcinoma.

A 67-year-old man presented for an evaluation after experiencing right hypochondrial pain lasting for two months. Abdominal ultrasonography showed a hepatic tumor in the right liver and extremely mild hepatic steatosis. The imaging findings indicated that the tumor (43 mm in size) was ischemic, and the lesion was surgically resected and examined. The histopathological findings demonstrated 95% necrosis with moderately differentiated hepatocellular carcinoma (HCC). The diagnosis was HCC with spontaneous regression. There was also pathological evidence of thrombus formation in the peripheral arteries and portal veins. In addition, the non-cancerous regions of the liver were diagnosed as exhibiting non-alcoholic steatohepatitis. The pathological findings obtained after resection of the HCC lesion showed spontaneous regression.