CD25, an interleukin-2 receptor (IL-2R) alpha subunit, is expressed in adult T-cell leukaemia, cutaneous T-cell lymphoma, ALCL, and hairy cell leukaemia and on Reed-Sternberg and associated polyclonal T-cells in HL. The gene discussed is IL2RA; the disease is primary cutaneous T-cell non-Hodgkin lymphoma.