An unusual hepatocellular carcinoma: an ultrastructural and immunohistochemical study.

This paper describes a 50-year-old woman with an unusual malignant tumour of the liver. Poorly differentiated liver cells, tubular structures and spindle cells in abundant intercellular ground substance characterized the tumour. Extremely high serum concentration of alpha-fetoprotein was present. The spindle cells showed strong immunoreactivity against this antigen and vimentin. Both the spindle and epithelial cells showed negative immunoreactivity against desmin, epithelial membrane antigen and keratin. Markers for low molecular cytokeratin (MAK-6, CAM 5.2) were demonstrated in both cell types. Ultrastructurally the neoplastic epithelial cells showed frequent intercellular spaces and well-formed brush borders suggestive of differentiation towards hepatocytes and bile duct epithelium. The immunohistological findings established the epithelial nature of the spindle cells thus distinguishing the tumour from hepatoblastoma.