Sarcomatoid hepatocellular carcinoma with osteoclast-like giant cells: case report and immunohistochemical observations.

Hepatocellular carcinoma (HCC) with osteoclast-like giant cells (OGC) developed in the cirrhotic liver of a 42-year-old male. Serum protein induced by vitamin K absence or antagonist II was elevated preoperatively. The patient died of the disease on the 28th postoperative day. Histologically, the tumor consisted of OGC and mononuclear cells (MC). The OGC were characterized by benign-appearing nuclei, whereas the MC had atypical nuclei with a considerable number of mitoses. A vaguely trabecular pattern was observed in the focal area of the tumor, but no evidence of overt HCC was found. Immunohistochemical analysis revealed that both OGC and MC were diffusely positive for histiocytic and mesenchymal markers. Some MC were focally positive for cytokeratins 7, 8 and 19, and for albumin. Our clinical, histological and immunohistochemical findings suggest that the MC were derived from hepatocytes, with some mesenchymal features, but the OGC were non-neoplastic and reactive histiocytes.