Proliferating cell nuclear antigen immunoreactivity in cervical intraepithelial neoplasia and benign cervical epithelium.

In the normal ectocervix, mitoses are rare and are usually confined to the basal layers. In contrast, they occur more frequently in cervical intraepithelial neoplasia (CIN) and are seen at higher levels, suggesting that CIN may be associated with a progressive dysfunction in proliferative activity of cervical cells. The objective of this study was to use proliferating cell nuclear antigen (PCNA) immunohistochemistry to examine the proliferative activity of cervical epithelial cells in CIN lesions. Sixty-eight cervical biopsies were examined; 20 were totally benign, 14 had CIN I, 21 CIN II, and 13 CIN III. In benign epithelia, PCNA staining was usually confined to the basal layers, whereas in CIN the staining was seen at progressively higher levels of the epithelium. There was a statistically significant correlation between the CIN grade and the highest level of PCNA staining (PCNA grade, r = 0.746, P < 0.001). In addition, the PCNA grade showed significant correlation with the highest level at which mitoses were seen (mitosis grade, r = 0.706, P < 0.001), and a strong direct correlation between the mitosis and CIN grades was also observed (r = 0.955, P < 0.001). These data demonstrate that (1) PCNA immunoreactivity in neoplastic cervical epithelium is different from that seen in the normal cervix, suggesting that CIN is associated with a dysfunctional proliferation of cervical epithelium, (2) that there is a significant correlation between the PCNA grade and CIN grades, and (3) the "mitosis grades" have a strong correlation with the CIN grades.