ALCLs with DUSP22 rearrangements show diminished expression of PD-L1 and overexpress CD58. (A) DUSP22-rearranged ALCLs show reduced expression of CD274 (encoding PD-L1) and increased expression of the costimulatory gene CD58. Significant differences in expression of PDCD1 (encoding PD-1) or PDCD1LG2 (encoding PD-L2) were not observed. P values, Wilcoxon test; n.s., not significant. (B) CD274 gene expression correlates with STAT3 gene expression in ALCL. Spearman ρ = 0.63; P = .0001. (C) Immunohistochemistry for PD-L1 in ALK-positive ALCL and DUSP22-rearranged ALCL. Original magnification, ×400. (D) DUSP22-rearranged ALCLs show significantly less tumoral staining for PD-L1 protein than either ALK-positive ALCL or other ALK-negative ALCLs (Wilcoxon test).