Acute lymphoblastic leukemia. Possible origin from a mediastinal germ cell tumor.

The case of acute lymphoblastic leukemia developing shortly after the diagnosis and treatment of a mediastinal germ cell tumor, is reported. The close temporal relationship of these two rare diseases and the presence of a population of mononuclear cells with features of lymphoblasts in the resected germ cell tumor, suggest that the leukemic process originated from the mediastinal tumor.