CD274 and neoplasm: In HNPGLs treated with embolization prior to surgery (n = 7), the median expression of PD-L1 in tumor cells was significantly higher with 15% (range 0% to 60%) as compared to a median PD-L1 expression of 0% (range 0% to 1%) in HNPGLs without embolization prior to surgery (n = 7; p = 0.008) (Figure 2).