STAT3 and primary cutaneous T-cell non-Hodgkin lymphoma: Furthermore, to verify whether STAT3/5 copy number gains are associated with elevated expression of STAT3 and STAT5A/B, we performed RT–qPCR on mRNA isolated from peripheral blood mononuclear cells (PBMCs) of L‐CTCL patients (n = 5) and healthy donors (n = 9).