In addition, STAT3-mutated T/NK-LGLL cases also required treatment more frequently (12/24, 50% vs. 4/44, 9%; p = 0.0001), due to the associated-autoimmune diseases (e.g., severe neutropenia); consequently, they also showed a significantly shorter time-to-(first) therapy after a median follow-up of 183 months: median (95% confidence interval) of 72 months (1–180) vs. not reached, respectively (p = 0.0001; Table 3), which was more evident in non-Y640F STAT3-mutated cases—2 months (1–6) vs. 93 months (59–127) in Y640F-mutated cases; p = 0.009. The gene discussed is STAT3; the disease is neutropenia.