ADULT T-CELL LEUKEMIA FOLLOWING HTLV-I-ASSOCIATED MYELOPATHY TROPICALSPASTIC PARAPARESIS - CASE-REPORTS AND IMPLICATION TO THE NATURAL COURSE OF ATL

Adult T cell leukemia (ATL) is the T cell malignancy caused by human T lymphotropic virus type I (HTLV-I), and HTLV-I is also the causative agent of HTLV-I-associated myelopathy/tropical spastic paraparesis (HA M/TSP). Although HTLV-I causes both diseases, concomitant occurrence i s reported to be rare. This paper describes two cases of HAMTTSP that developed into lymphoma-type ATL after the onset of HAM/TSP. In one ca se, the same HTLV-I infected clone could be detected by polymerase cha in reaction in peripheral blood obtained when the patient was diagnose d as HAM/TSP. This finding showed that the HTLV-I clone already existe d at the stage of HAM/TSP. Since frequent detection of clonal prolifer ation of HTLV-I infected cells has been reported previously in patient s with HAM/TSP, careful follow-up is needed for patients with HAM/TSP.