CD274 and breast carcinoma: Therefore, the aim of this study was to evaluate and examine possible differences in the tumor microenvironment composition and PD-L1 expression as well the prognostic significance of CD4, CD8, CD68, and CD163 in <i>PIK3CA</i> mutated and non-mutated hormone receptor positive and HER2 negative (HR+/HER2-) breast carcinoma.