STAT3 and T-cell large granular lymphocyte leukemia: CIN shows a similar clinical picture to other entities associated with clonal expansion of cytotoxic T lymphocytes, e.g., myeloid failure syndromes and T-LGL leukemia, and the low frequency of STAT3 gene mutations in CIN patients and the absence of specific immunogenic characteristics of mutants versus unmutated patients imply that CIN is a distinct entity from the other T/NK diseases, although the spectrum of their clinical manifestations shows overlap [31,46,96].