Carey CD, et al. - This study was designed to detect whether topological analysis revealed a PD-L1 associated microenvironmental niche for Reed-Sternberg cells in Hodgkin lymphoma. A unique topology of classical Hodgkin lymphoma (cHL) was defined. In this, PD-L1+ tumor-associated macrophages (TAMs) surrounded Hodgkin Reed-Sternberg (HRS) cells and implicated CD4+ T-cells as a target of programmed cell death protein 1 (PD-1) blockade.