Upregulation of INK4a gene occurs in vulvar carcinogenesis. p16(INK4a) is not a sensitive marker for differentiation of benign vulvar squamous epithelium from condyloma acuminatum or VIN 1 lesions because most VIN 1 lesions are p16(INK4a) negative. Expression of p16(INK4a) may aid in the diagnosis of HPV-related lesions and as such may be of value as a surrogate marker in the diagnosis of vulvar premalignant and malignant lesions.

Early invasive vulvar squamous cell carcinoma (SCC) with less than 1.0 mm of invasion (FIGO stage IA) has been shown to have a minimal risk of lymph node metastasis and is associated with an excellent prognosis. The prognostic significance of other histologic parameters other than depth of invasion, however, remains controversial. Seventy-eight consecutive cases of vulvar SCC having a depth of invasion of 5.0 mm or less were reviewed and the clinical outcome compared with the type of surgical excision, the presence of concurrent lymph node metastases, the depth of tumor invasion, the tumor thickness, the tumor horizontal spread, the estimated tumor volume, tumor histologic subtype, tumor histologic grade, tumor pattern of invasion, tumor multifocality, presence of perineural invasion, presence of angiolymphatic invasion and the presence of precursor lesions, including the type of vulvar intraepithelial neoplasia and presence of lichen sclerosus. The only histologic feature for predicting concurrent lymph node metastasis was tumor depth of invasion. The 3 most important features of stage IA tumors in predicting tumor recurrence were the depth of invasion, presence of SCC at the surgical margins, and the histologic grade.

Context.—The protein p16Ink4a is overexpressed in cervical lesions associated with high-risk human papillomavirus (HPV) subtypes 16 and 18, but not in low-risk HPV subtypes 6 and 11 or non–HPV-associated cervical lesions. Objective.—To determine whether p16Ink4a expression in equivocal cervical lesions helps distinguish atypical non-HPV changes from HPV-related changes. Design.—One hundred ninety-one cervical lesions, including 81 cervical intraepithelial neoplasia 1, 52 squamous metaplasia, 33 cellular features suggestive of HPV-related change, 9 reserve cell hyperplasia, 4 microglandular hyperplasia, and 12 inflammatory cervicitis, were randomly selected from archival cervical biopsy specimens. All 191 samples were studied with p16Ink4a (JC8 monoclonal antibody). Reactivity for p16Ink4a was scored on a 3-tier system as follows: negative, 0% to 5% cells reactive; focal/scattered positive, greater than 5% and less than or equal to 80% cells reactive; diffuse positive, greater than 80% cells reactive. Reactivity was based on normal/reactive cervical specimens where anti-p16 antibody was negative/weakly expressed in non–cervical epithelial cells. Cervical intraepithelial neoplasia 1 lesions not reactive for p16Ink4a were investigated for the presence of high-risk HPV by real-time polymerase chain reaction. Results.—No p16Ink4a reactivity was detected in the cervical lesions associated with atypical non-HPV change. Eleven of the cervical intraepithelial neoplasia 1 lesions showed focal/scattered reactivity expression for p16Ink4a, and 19 of the CIN 1 lesions had diffuse reactivity. Fifty of 51 of the CIN 1 lesions negative for p16Ink4a were real-time polymerase chain reaction negative for the presence of high-risk HPV; 1 was real-time polymerase chain reaction positive for high-risk HPV. Conclusions.—The data support the routine use of p16Ink4a immunohistochemical evaluation of cervical biopsy specimens for better discrimination of non–HPV-associated lesions from HPV-related lesions.