KRT5 and squamous cell carcinoma: The pathological report of the mass in left lobe of thyroid gland showed that it has been squamous cell carcinoma, and the immunohistochemical results demonstrated that malignant cells were positive for CK7 (regional positive), P40, CKpan, CK5/6, EMA, P16, PD-L1 (22C3) (CPS: > 50), EGFR, and negative for Calcitonin, CD117, CD5, CD56, CgA, CK20, Pax-8, SYN, Tg, NapsinA and TTF-1 immunohistochemical markers (Figure 1G).