[Clinical and Immunophenotypic Properties of Small Cell Variant of T-cell Prolymphocytic Leukemia]

To investigate the clinical, morphologic and immunophenotypic properties of the patients with small cell variant of T-cell prolymphocytic leukaemia(T-PLL).

Peripheral blood and bone marrow cytomorphologic and immunophenotypic examination, and T-cell receptor(TCR) gene rearrangement detection were used to verify the diagnosis for 2 patients with lymphocytosis. Two patients were treated with combined chemotherapeutic protocol based on fludarabine.

At diagnosis of case 1, the main lymphocytes of peripheral blood smear were the small mature lymphocytes without nucleoli. The immunophenotype of the cells was CD3⁺CD5⁺CD7⁺CD4⁺CD8⁺TCRα/β⁺. The patient achieved complete remission after treatment with combined with CTX of fludarabine. The disease relapsed at 32 months after diagnosis. The abnormal lymphocytes were medium-sized ones with a visible nucleolus. Immunophenotyping showed that the leukemic cells were predominantly CD8 positive(CD3⁺CD5⁺CD7⁺CD4^-CD8⁺TCRα/β⁺). Both the peripheral blood and bone marrow cells of case 2 were predominanthy the mature lymphocytes, and their immunophenotype was HLA-DR⁺CD7⁺CD5⁺CD4⁺CD3⁺CD2⁺CD56⁺cCD3⁺TCRα/β⁺. The combined fludarabine therapy was ineffective.

Immunophenotypical switch from CD4⁺CD8⁺ to CD4^-CD8⁺ may be associated with a poor response to chemotherapy. CD56 expression is an independent poor prognostic factor for primary refractory disease in T-PLL and may be considered for implementing risked-adapted therapeutic strategies.