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

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

METHODS: 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.

RESULTS: 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.

CONCLUSION: 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.