Patients with CK20 (umbrella cell +) may have uroepithelial cell carcinoma or reactive urothelial cell hyperplasia and require further testing. Patients with either uroepithelial cell carcinoma or reactive urothelial cell hyperplasia may have CK20 (umbrella cell +) and require further testing. The former if the deep cells are positive and the latter if only the surface cells are positive. However, patients need to undergo further medical investigations, such as urological CT, MRI, cystourethroscopy, or ureteroscopy or flexible ureteroscopy, to determine the exact location of the tumor and to clarify the exact type of pathology and the benign or malignant nature of the tumor by biopsy. CK20 exists in normal gastrointestinal epithelium, migratory epithelium and Merkel cells, and can be used to identify uroepithelial carcinoma, reactive urothelial hyperplasia, and can also be used in combination with CK7 as an indicator of the primary site of the cancer, and used in the diagnosis of Merkel cell carcinoma. In case of abnormal test results, it is recommended to consult a doctor in time to clarify the cause of the disease with the help of a doctor and carry out targeted treatment or therapy.