Malignant germ cell tumor of the anterior mediastinum with leukemia-like infiltration.

We present here a rare autopsy case of malignant germ cell tumor with leukemia-like infiltration of the anterior mediastinum in a 35-year-old male. Chest X-rays revealed an abnormal mediastinum, which was diagnosed as thymoma. During the course of treatment, huge abnormal cells 40-50 mu in size were found in the peripheral blood smear and disseminated bone metastasis of the malignant thymoma was suspected. The tumor was resistant to both chemotherapy and radiotherapy. The patient died of respiratory failure. The autopsy disclosed a huge tumor measuring 24 X 13 X 10 cm in the anterior mediastinum. Histological findings of the tumor revealed cells which had spread to almost all organs, indicating leukemia-like infiltration. This pattern of metastasis has been reported in the cancer of non-hematologic origin under the term "carcinocythemia (CCA)". To our knowledge, the present case is the first report of a leukemia-like infiltration in case of malignant germ cell tumor. Careful serial section revealed no primary foci in either testis.