ALK and Sezary syndrome: PD-L1 expression has been found to be higher in a variety of T-cell lymphomas, including AITL, ATLL, ALCL (anaplastic lymphoma kinase [ALK]-positive and -negative), ENKTL, MF, Sézary syndrome and PTCL-not otherwise specified (PTCL-NOS) [14,15,16].