CD20-positive adult T-cell leukemia.

A 67-year-old woman was admitted to our hospital because of lymphadenopathy and lymphocytosis. Monoclonal integration of HTLV-I provirus DNA was detected, and a diagnosis of adult T-cell leukemia (ATL) was made. Flow cytometry revealed that the ATL cells expressed CD20 as well as T-cell-associated antigens, and expression of CD20 mRNA was also demonstrated. A novel T-cell subpopulation expressing CD20 molecules has recently been identified. This is the first report of CD20-positive ATL, suggesting that HTLV-I can infect and transform CD20-positive T cells.