IFNG and primary cutaneous T-cell non-Hodgkin lymphoma: In Chennareddy et al.’s 2025 study, both chronic idiopathic erythroderma and erythrodermic CTCL had keratinocytes and fibroblasts with upregulated MHC II genes (HLA-DRB1, HLA-DRA, and CD74), likely in response to IFN-γ [35].