On the other hand, and contrary to de novo DLBCL, rare PD-L1 expression but high PD-1 expression are observed in the large neoplastic B cells in Richter syndrome (RS), which represents transformation of chronic lymphocytic leukemia (CLL) to DLBCL with dismal prognosis [179,180,181]. Here, CD274 is linked to X-linked retinoschisis.