An Emerging Anti-p16 Antibody-BC42 Clone as an Alternative to the Current E6H4 for Use in the Female Genital Tract Pathological Diagnosis: Our Experience and a Review on p16ink4a Functional Significance, Role in Daily-Practice Diagnosis, Prognostic Potential, and Technical Pitfalls

Background: To date, useful diagnostic applications of p16 IHC have been documented in\r\ngynecological pathology both for HPV-related and non-HPV-related lesions. In the present article,\r\nwe reported our experience with the novel anti-p16 INK4a antibody (clone BC42), whose expression\r\nwas tested across all different gynecologic neoplasms; we also compared it to the traditional\r\nE6H4 clone. Moreover, we discussed and explored all the diagnostic applications of p16 IHC in\r\ngynecologic pathology. Methods: Consultation cases covering a 5-year period (2016–2020) regarding\r\ngynecological neoplastic and non-neoplastic lesions in which immunohistochemistry for p16, clone\r\nE6H4 was originally performed, were retrospectively retrieved from the files of our institution.\r\nImmunohistochemical staining for p16ink4a (BC42) [Biocare Medical group-Paceco USA; Bioptica\r\nMilan] and p16ink4a (E6H4) [Ventana Medical Systems-Arizona USA; Roche] was performed by\r\nusing the Ventana automated immunostainer (Ventana Medical Systems, Tucson, AZ, USA). The immunostaining\r\npattern was defined as negative, focal/patchy, or diffuse. Results: A total of 196 cases,\r\nrepresented by 36 high-grade SIL/CIN3 of the uterine cervix, 30 cervical adenocarcinomas, 22 cervical\r\nsquamous cell carcinoma, 70 endometrial carcinomas, 25 high grade serous ovarian carcinomas,\r\n6 uterine adenomatoid tumors, and 10 uterine leiomyosarcomas were included in this study. Results\r\nshowed concordant staining quality of both clones on all tested neoplastic tissues. Conclusions:\r\nThe novel anti-p16 antibody (BC42 clone) appeared as an alternative to the current E6H4 for use in\r\ngynecological neoplasms, offering similar levels of positivity and equally reliable staining results.