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 × 10⁹/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.