Adult T-cell leukemia-lymphoma.

Adult T-cell leukemia-lymphoma, an aggressive T-cell leukemia, is characterized by the presence in the peripheral blood of malignant T cells that have highly indented or lobulated nuclei. Phenotypically the cells are usually helper T cells, but functionally they behave as suppressor cells. Patients have skin and lung involvement, hepatosplenomegaly, moderate lymphadenopathy sparing the mediastinum, and various metabolic abnormalities such as hypercalcemia. The clinical course may be chronic or acute, usually followed by a rapidly progressive terminal course. Adult T-cell leukemia-lymphoma is now known to be caused by human T-cell lymphotropic virus type I, which has been identified in the cells of patients with the disease.