Transformed aggressive γδ-variant T-cell large granular lymphocytic leukemia with acquired copy neutral loss of heterozygosity at 17q11.2q25.3 and additional aberrations.

T-cell large granular lymphocytic leukemia (T-LGLL) is a rare indolent lymphoproliferative disorder characterized by cytopenias, splenomegaly, and various degrees of T-cell lymphocytosis, due to a clonal expansion of CD8-positive cytotoxic T-cells. Phenotypic variants of T-LGLL include CD4(+) /CD8(-) T-cells, with dual CD4(-) /CD8(-) /γδ(+) T-cells being even rarer. Cytogenetic abnormalities in T-LGLL have rarely been reported, and there is scientific debate regarding the existence of aggressive or transformed variants of T-LGLL. We report a patient with T-LGLL, γδ variant, with nearly 20-year-long duration of cytopenias before transformation to an unusual clinical scenario, manifesting with marked lymphocytosis >100 × 10(9) /L and infiltration of lymph nodes, tonsils, and subcutaneous tissue. Single-nucleotide polymorphism assays revealed acquired copy neutral loss of heterozygosity at 17q and deletion of 3p21.31, in addition to trisomy 5, monosomy X, and monosomy 21. These genetic abnormalities provided a better understanding of the molecular nature and the potentiality of disease transformation.