CD8A and squamous cell intraepithelial neoplasia: The expression levels and distribution of B7-H4 (VTCN1), PD-L1 (CD274), CD4 (CD4), and CD8 (CD8A) were examined using immunohistochemistry (IHC) and spatial transcriptomics (ST) analysis of the HNSCCs, adjacent normal mucosa (NOM), and squamous intraepithelial neoplasia (SIN).