Differentiating high-grade cervical intraepithelial lesion from atrophy in postmenopausal women using Ki-67, cyclin E, and p16 immunohistochemical analysis.

Objective: In postmenopausal women, differentiating high-grade cervical intraepithelial neoplasia (CIN 2,3) from atrophic uterine cervical squamous epithelium histologically may pose a diagnostic challenge. Recent studies have indicated the value of using a combination of Ki-67, cyclin E, and p16 immunohistochemical analysis in recognizing CIN 2,3. In this study, we compared the staining features of Ki-67, cyclin E, and p16 in cervix specimens from postmenopausal women to distinguish CIN 2,3 from atrophy.

Methods: Twenty-six formalin-fixed paraffin-embedded archival cervical specimens (4 biopsy, 8 laser cone, and 14 total hysterectomy samples) were selected from 25 women 50 to 80 years of age (mean = 64 years). Cases included CIN 2,3 (n = 10), atrophy (n = 9), and coexistent CIN 2,3 and atrophy (n = 6). Slides were stained with monoclonal antibodies to Ki-67, cyclin E, and p16 using the avidin-biotin-peroxidase method. Strength of staining was graded as 1+ to 3+. Pattern of staining was described as diffuse, patchy, or scattered. Ki-67 staining restricted to the basal/parabasal zone was scored as negative.

Results: All CIN 2,3 cases demonstrated variable positivity for Ki-67, cyclin E, and p16. Most CIN 2,3 cases showed strong p16 (81.3%) and Ki-67 (75.0%) reactivity, while only 31.3% of them showed strong cyclin E activity. Some CIN 2,3 cases demonstrated strong p16 but weak Ki-61 and cyclin E reactivity. All atrophic epithelia were negative for p16, cyclin E, and Ki-67. In coexistent CIN 2,3 and atrophy cases, the three-antibody panel clearly demarcated the transition from benign to neoplastic epithelia.

Conclusion: P16 is the most valuable marker followed by Ki-67 for differentiating CIN 2,3. While cyclin E appears to add limited value on these two markers. Therefore, although the three-antibody immunohistochemical panel (p16, Ki-67, and cyclin E) can be a valuable adjunct to routine hematoxylin-eosin staining, it is also possible to use the two-antibody panel (p16 and Ki-67) to effectively distinguish CIN 2,3 from atrophy in postmenopausal women.