KLK3 and cancer: This case met three of the core diagnostic criteria of Mott et al. (5): examination of: continuous sections confirmed that the tumor's squamous differentiation area reached 95% (Figure 2A); whole-body PET-CT (imaging number: A016DX2206010175) excluded metastatic squamous carcinoma; and serum and prostate-specific antigen (PSA) were both negative in the cancer tissue (Figure 2B).