Small cell carcinoma of the liver: a hitherto unreported variant of hepatocellular carcinoma

We report three cases of an unusual primary carcinoma of the liver composed of small cells. The patients were adult males (56 to 89 years) who presented with jaundice, weight loss and abdominal discomfort. Surgery was attempted in one case. Clinical evolution was rapid, with death ensuing between 1 and 5 months after diagnosis. Surgical (1 case) and autopsy (2) tissues were available for review. All three tumours arose in non-cirrhotic livers. They were composed of broad nests of small epithelial cells with little supporting tissue. They were positive for low-molecular weight keratins and alpha-fetoprotein. One case was immunoreactive for erythropoietin antigen. Expression of neuroendocrine markers was focal and erratic. No immunostaining was observed for carcinoembryonic antigen or S-100 protein. In one case ultrastructural investigation disclosed canaliculi surrounded by microvilli and junctional complexes. In the light of these features, it appears that small cell carcinoma represents a rare, but definite variant of hepatocellular carcinoma. Although it does not segregate in a peculiar clinical setting, it should be distinguished from metastatic pulmonary small cell carcinoma as well as from other malignancies featuring small cells.