It was therefore to be expected that the possibility to investigate the topographical organization in tumors [3] is also applied in HL, because signaling between programmed cell death protein 1 (PD-1) and the PD-1 ligands (PD-L1, PD-L2) is essential for RS-cells to evade anti-tumor immunity in cHL. This evidence concerns the gene PDCD1 and classic Hodgkin lymphoma.