CD274 and neoplasm: PD-L1 staining in tumor cells is associated with the papillary subtype (p < 0.001, correlation coefficient 0.242), a high grade tumor (G3, p = 0.029, not significant with Bonferroni correction, correlation coefficient 0.120), or secondary metastatic diseases (p = 0.030, not significant with Bonferroni correction, correlation coefficient 0.125).