CD3-negative, CD20-positive T-cell prolymphocytic leukemia: Case report and review of the literature

We report a case of CD3-negative, CD20-positive T-cell prolymphocytic leukemia (T-PLL). The leukemic cells were of medium-to-large size, mature-looking, and did not have cytoplasmic granules. The leukemic cells were negative for surface CD3, CD2, and CD7 and strongly positive for CD20. T-cell lineage markers such as CD4, CD5, and cytoplasmic CD3 were also positive. A monoclonal rearrangement of the T-cell receptor (TCR) beta chain gene was detected. CD3-negative T-PLL has been reported often, but CD20-positive T-PLL has not. We reviewed seven cases of CD20-positive immature and mature T-cell leukemias, including the present case. Three were immature T-cell leukemias (acute lymphoblastic leukemia), and four were mature T-cell leukemias (granular lymphocytic leukemia, small lymphocytic lymphoma/chronic lymphocytic leukemia, adult T-cell leukemia, and the present case). Splenomegaly was a common feature. However, our case alone had "bright" CD20 expression on the leukemic cells. This is the first report of CD20(+) T-PLL.