Pathology and immunology of adult T-cell leukemia/lymphoma.

Adult T-cell leukemia/lymphoma is a disseminated malignancy of T lymphocytes infected by the human T-lymphotrophic virus type I. It is endemic in southern Japan, the Caribbean basin, the southeastern United States, and central Africa. The virus is transmitted through intimate contact or exposure to blood products; only a small proportion of those infected develop adult T-cell leukemia/lymphoma. The malignant cells are activated T-helper cells that have suppressor function and multiple cytogenetic abnormalities. The disease occurs in mid to late life, years after exposure to the human T-lymphotrophic virus type I, with hypercalcemia, skin involvement, lymphadenopathy, hepatospenomegaly, lytic bone lesions, and leukemia. Although the disease usually has a rapidly progressive clinical course, there is a spectrum of clinical and pathologic features with smoldering and subacute forms. Our knowledge of this malignancy has grown rapidly and is leading to greater understanding of the relationships between human retroviruses and oncogenes.