CD20- and CD56-positive T-cell large granular lymphocyte leukemia in a human T-cell leukemia virus type 1 carrier.

A 60-year-old man was diagnosed with asymptomatic T-cell granular lymphocyte (T-LGL) leukemia in September 2006. He was serologically positive for human T-cell leukemia virus type 1 (HTLV-1). However, monoclonal integration of the HTLV-1 genome was not detected in the peripheral blood, suggesting that HTLV-1 did not contribute to the pathogenesis of T-LGL leukemia in the present case. Phenotypically, neoplastic cells of our case were CD3+, CD4*, CD8+, CD16-, CD56+, CD57*, and T-cell receptor (TCR) alphabeta+. They also coexpressed CD20 antigen with weak intensity. This represented a unique case of T-LGL leukemia showing a typical clinical and phenotypic features.