CK （Pan） mainly marks keratinized epithelium, stratified squamous epithelium, stratified epithelium, proliferative keratinocytes, and monolayer epithelium, and is used in squamous cell carcinoma （including Spindle variant）, various adenocarcinoma （including adrenal carcinoma and hepatocellular carcinoma）, transitional cell carcinoma, small cell carcinoma, malignant mesothelioma, germ cell tumor （excluding spermatogonium Tumor, partial synovial sarcoma, and leiomyosarcoma can be positively labeled. Pathology is mainly applied to the differential diagnosis of epithelial tumors and nonepithelial tumors.