Leukemias associated with human T-cell lymphotropic virus type I in a non-endemic region

Human T lymphotropic virus type 1 (HTLV-I) is a retrovirus which is prevalent in southern Japan, the Caribbean Basin, and Africa. Recent seroprevalence studies in the United States suggest that there are about 50,000 infected individuals. The identification of 5 individuals with HTLV-I-associated leukemia/lymphoma referred to our center with relatively limited screening methods suggests that these disorders are more common than currently appreciated. Though 99% of infected individuals remain asymptomatic, this virus may cause immunosuppression, lymphomas, or myelopathy. The lymphomas have been classified as acute or chronic forms of adult T cell leukemia-lymphoma (ATLL). Acute ATLL is a T cell form of non-Hodgkin's lymphoma in an HTLV-I-infected individual with leukemia, skin infiltration, or hypercalcemia. This disorder is poorly responsive to chemotherapy and all patients should be referred for experimental protocols. Chronic ATLL is an insidious disease characterized by lymphadenopathy, skin infiltration of less than 10% of the body surface, and/or atypical lymphocytes with highly convoluted nuclei which include 1 to 10% of the nucleated cells in the peripheral blood, but no visceral involvement or hypercalcemia. The prognosis of these patients is not clearly defined. All individuals with mature T lymphocytic malignancies should be evaluated with HTLV-I-specific assays. The most sensitive and specific assays available include the enzyme linked immunoadsorbent antibody assay (ELISA) and the polymerase chain DNA amplification reaction assay. With improved laboratory techniques and greater awareness of the characteristics of this disease by clinicians, it is likely that the natural history of HTLV-I infection will be better defined, and improvements in therapeutic management will be developed.