KRT5 and squamous cell carcinoma: Histopathological evidence of squamous cell carcinoma (Figure 1F). Subsequent immunohistochemical analysis demonstrated positive staining for CK5/6, CK8, CEA, P16 (Figure 1G), and E-cadherin markers, while showing negative reactivity for P40 (Figure 1H), CK(L), and P53. PD-L1 CPS 12 (Figure 1I). The proliferation index assessed by Ki-67 immunostaining reached approximately 80% positivity.