The occurrence and development of the cervix is a process from quantitative to qualitative change, evolving gradually to a sudden shift over a long period. The precursor might be the heterotypic zone of the cervix, which is a common site for abnormalities. During the formation of this heterotypic zone, cervical epithelial metaplasia is relatively active, and, compounded by infection with the human papillomavirus and further stimulated by external carcinogens, immature or proliferative squamous epithelial cells may exhibit gradual changes or atypical hyperplasia, potentially leading to sarcomatoid changes in the cervical epithelium. This might be a precursor sign.