Spontaneous regression of hepatocellular carcinoma--a case report.

Spontaneous regression of cancer is a rare phenomenon seldom described in patients with hepatocellular carcinoma. A 54-year-old Korean woman suffered from cytologically-proved advanced hepatocellular carcinoma, for which she received no treatment. Papanicolaou's smears revealed high cellularity. Many clusters of polygonal cells showed long, thick anastomosing cords covered by flattened endothelial cells. The polygonal cells showed small hepatocytoid appearance, characterized by increased nuclear/cytoplasmic ratio. She remained in good clinical condition and, at 4 years of follow-up, the hepatocellular carcinoma could not be visualized radiologically. To date, only 14 case reports of apparently spontaneous regression of hepatocellular carcinoma have been published in the English literature. The mechanisms underlying this intriguing phenomenon remain unknown.