Mediastinal germ cell tumor with acute myeloid leukemia and growing teratoma syndrome.

A 39-year-old man was referred to hospital with a giant mediastinal mass, thrombocytopenia and high levels of serum tumor markers. Flow cytometry of bone marrow and peripheral blood samples led to the diagnosis of a mediastinal germ cell tumor associated with hematologic neoplasia. He was treated with combination chemotherapy for a germ cell tumor and acute myeloid leukemia. After chemotherapy, the tumor was enlarged, although serum tumor marker levels had decreased. After induction therapy, the tumor was surgically resected. This syndrome is rare, and more cases need to be studied to enable effective treatment.