STAT3 and T-cell large granular lymphocyte leukemia: While STAT3 mutations have been described in 40% of T-cell large granular lymphocytic leukemia (T-LGL)34, in 30% of chronic lymphoproliferative disorders of natural killer cells35, and in roughly 10% of subsets of T-cell lymphoma36, STAT3 mutations are rare in B-cell lymphomas28,37,38.