Microinvasive carcinoma of the cervix: site of first focus of invasion.

Abstract

To evaluate the topography of the first invasive focus in microinvasive squamous cell carcinoma of the uterine cervix. We studied 120 formalin-fixed and paraffin-embedded cold-knife conization specimens processed as step-serial sections. Four types of microinvasion were distinguished according to site: type I (ectocervical outside the last cervical gland), type II (ectocervical between the external os and the last gland and in connection with the surface epithelium), type III (ectocervical between the external os and the last gland but deep in cervical glands), and type IV (intracervical and in connection with the surface epithelium). A total of 142 early invasive foci were seen in the 120 cones. A single focus was seen in 106 (88%) specimens, whereas 14 (12%) had more than one focus. The foci were classified as type I in 16 (11%), type II in 31 (22%), type III in 70 (49%), and type IV in 25 (18%) cases. One half of the early invasive foci originated at the surface epithelium (types I, II, IV), either at the ectocervix (types I, II) or in the endocervix (type IV).