Abnormal lymphocytes in cutaneous T-cell lymphoma [CTCL; including mycosis fungoides (MF)] were characterized by CD4 restriction, variable loss of CD7 and CD26, moderate CD2, moderate-to-dim surface CD3 and CD5, and heterogeneous CD279 (PD1) but negative expressions of CD8, CD10, CD16, CD56, CD57, CD185 (CXCR5), and TCRγδ. Here, DPP4 is linked to mycosis fungoides.