Des-gamma-carboxy prothrombin (PIVKA-II)-producing mediastinal embryonal carcinoma with features of hepatoid differentiation.

The case of a 48-year-old man with primary nonseminomatous embryonal carcinoma at the posterior mediastinum is described. The patient displayed extremely high plasma levels of Des-gamma-carboxy prothrombin (PIVKA-II) (4040 mAU/ml). Ultrasonography and dynamic computed tomography ruled out hepatocellular carcinoma (HCC) or liver metastasis. After preoperative systemic chemotherapy, total tumor resection was performed. Postoperatively, the plasma levels of PIVKA-II returned to within the normal range (24 mAU/ml). An immnohistochemical study using anti-PIVKA-II monoclonal antibody revealed the cytoplasmic expression of PIVK4-II in the carcinoma cells. These results indicate that tumor cells, which are manifested as hepatoid differentiation, may produce PIVKA-II. This case seems to be the first case reported in which PIVKA-II was produced by nonseminomatous mediastinal embryonal carcinoma without HCC or liver metastasis.