T-Cell Prolymphocytic Leukemia, Small Cell Variant, Possibly at the Stage of Intracytoplasmic Expression of CD3 in T-Cell Ontogenesis.

T-cell prolymphocytic leukemia, small cell variant (T-PLL-s), is a rare lymphoid neoplasm associated with a poor prognosis. We encountered a case of T-PLL-s with a characteristic phenotype. A 67-year-old female was referred to our hospital because of lymphocytosis in August 2013. Hepatosplenomegaly, lymphadenopathy, and skin lesions were absent. Hematologic examination revealed a white blood cell count of 17.9 × 10(9)/L with 81.2% mature lymphocytes, which were small with a high nuclear/cytoplasmic ratio, lacking a nucleolus and cytoplasmic granules. Anemia and thrombocytopenia were not observed. Flow cytometric analysis showed that these lymphocytes were positive for CD2, cyCD3, CD4, CD5, CD7, CD21, and CD38 (partially), but negative for smCD3, smTCR-αβ and -γδ, cyTCR-β, CD1a, CD8, CD25, HLA-DR, and terminal deoxynucleotidyl transferase. Polymerase-chain reaction analysis of cells from both the peripheral blood and the bone marrow demonstrated monoclonal rearrangement of TCR-γ. A possible rearranged band of the TCR-β gene was observed by Southern blot analysis. The karyotype of the marrow cells was 46, XX. A diagnosis of T-PLL-s, possibly at the stage of cytoplasmic CD3 expression in the ontogenesis of T-cells, was made. The patient has been asymptomatic, and the white blood cell count has gradually increased during one-year observation, being 69.0 × 10(9)/L with 89.7% lymphocytes in August 2014.