Identification of human papillomavirus antigen in a bladder tumor.

Human papillomavirus (HPV) antigen was found in one of six noninfiltrating (grade II) carcinomas of the bladder. The antigen was located in the nuclei of the superficial cells. This virus-bearing tumor occurred in a patient with no known risk factors. The presence of HPV in low-grade urinary lesions seems to be frequent and may reflect the early stages of carcinogenesis; in fact, HPV infections may cause papillomas and carcinomas of the urothelial mucosae as well as the genital mucosae.