ABSTRACT
A variety of solid tumors can metastasize to bone marrow. In rare cases actual circulating neoplastic cells can be identified, accounting for usually only a low proportion of total white blood cells. It is well known that hematologic malignancies are often associated with mediastinal germ cell tumors, but huge tumor cell burden resulting in leukemia-like presentation is a very rare manifestation. We report here a case of malignant germ cell tumor with leukemia-like infiltration of bone marrow. A 19-year-old man was admitted for dyspnea for several months. Computer tomographic scan revealed that he had a huge mass at anterior mediastinum with a large amount of pleural effusion. His pleural fluid had many numbers of large, pleomorphic atypical cells. Peripheral blood also contained atypical cells with similar morphology. On bone marrow biopsy, diffuse infiltration of tumor cells were noted suggesting acute leukemia, but immunophenotyping ruled out the possibility of hematologic malignancy. His serum alpha-fetoprotein and beta-human chorionic gonadotropin levels were markedly elevated, which was consistent with the diagnosis of primary germ cell tumor. Cytogenetically the tumor cells showed hyper-triploidy. After induction chemotherapy with cisplatin, etoposide and bleomycin, the size of the tumor was regressed and the patient's symptoms were improved.