STAT3 and T-cell large granular lymphocyte leukemia: Although STAT3/5B mutations present in LGLL are discussed in the WHO 2016 classification of hematological malignancies [4], its routine (clinical) utility as “clonal” markers of disease—particularly in cases showing expansion of cytotoxic T cells other than TCD8+-LGLL (i.e., Tγδ+-LGLL)—still remains to be established [18,19,20,21,24,26,29].