Figure 1.

(A) PDL1 expression study of classical Hodgkin lymphoma with PDL1 (red chromogen)-MUM1p (brown chromogen) double-staining; note that a lot of PDL1⁺ cells, corresponding to tumor-infiltrating macrophages, do not express MUM1p while yielding dendroid cytoplasmic projections and form “immunosuppressive microniches,” in which PDL1 and MUM1p co-expressing Hodgkin- and Reed–Sternberg cells (see also inset) are scattered. (B) PD1 expression by single tumor cells (large ones) and plenty of tumor-infiltrating lymphocytes in T-cell- and histiocyte-rich B-cell lymphoma.