ECSIT and hemophagocytic syndrome: IKBKB and BIRC3, involved in the NF-kB pathway, are mutated at a low frequency, while the evolutionarily conserved signaling intermediate in Toll pathway (ECSIT) was subject to a hotspot mutation; ECSIT-V140A occurred in 17 of 88 (19%) ENKTLs and was associated with the activation of NF-kappa B, a higher incidence of hemophagocytic syndrome, and poor prognosis [92].