Fig. 3

Tumor immune microenvironment and high-risk human papillomavirus (HPV) infection status. (a) CD8-positive lymphocytes are densely arranged in the tumor and stroma. (b) CD4-positive lymphocytes can be observed primarily in the stroma. (c) Programmed cell death ligand-1 expression is detectable not only in tumor cells but also in inflammatory cells. The total positive score was 80. (d) High-risk HPV RNA in situ hybridization. Dot-like signals can be observed in tumor cells, suggesting viral gene integration into the tumor genome