Interestingly, activating mutations in JAK3 and its substrates STAT3 and STAT5 as well as deletions and/or loss of function of negative regulators such as SOCS1, SOCS3, and HNRNPK have been reported in CTCL [12,23,24,25]. This evidence concerns the gene STAT3 and primary cutaneous T-cell non-Hodgkin lymphoma.