PD-1 in cancer: Dr. Jekyll and Mr. Hyde

T cell non-Hodgkin lymphomas (NHL) represent about 6% of non-cutaneous lymphomas and 65% of cutaneous lymphomas (1). Recent insights into the genetic landscape of nodal T cell NHL have led to an update in their classification (2). Despite this advance, peripheral T cell lymphomas (PTCL) still show morphologic, phenotypic, genetic and prognostic heterogeneity.