T-cell large granular lymphocytic (LGL) leukemia consists of CD4(+)/CD8(dim) and CD4(-)/CD8(+) LGL populations in association with immune thrombocytopenia, autoimmune neutropenia, and monoclonal B-cell lymphocytosis

CD3(+)/CD57(+) T-cell large granular lymphocyte leukemia (T-LGLL) is an indolent neoplasm, exhibiting mostly CD8(+), less frequently CD4(+) phenotypes, and T-LGLL consisting of 2 populations with CD8(+) and CD4(+) phenotypes is markedly rare. An 87-year-old female was admitted under a diagnosis of immune thrombocytopenia (ITP) with a platelet count of 5.0×10(9)/L and increased number of LGL with unknown etiology. Her neutrophil count also decreased to 0.27×10(9)/L and she was positive for antineutrophil antibody. The WBC count was 2.7×10(9)/L with 34.7% LGL and flow cytometry (FCM) analysis revealed 16% CD3(+)/CD4(+)/CD8(dim)/CD57(+) and 20.9% CD3(+)/CD8(+)/CD57(+) populations. These populations also expressed granzyme B and perforin. Circulating mononuclear cells were found to be clonal by PCR analysis of T-cell receptor β-chain gene. Serum immunofixation and bone marrow FCM analyses demonstrated 2 clonal B-cells producing IgG-λ and IgA-λ. Deep amplicon sequencing of STAT3 and STAT5B genes revealed a STAT3 R302G mutation with an allele burden of 2.6%. The thrombocytopenia and neutropenia were successfully treated by prednisolone and romiplostim with negative conversion of antineutrophil antibody. This is the first reported case of T-LGLL with dual components of CD4(+)/CD8(dim) and CD4(-)/CD8(+) populations in terms of multiple comorbidities related to the respective CD8(+) and CD4(+) T-LGLLs.