Squamous Intraepithelial Lesions in Cervical Tissue Samples of Limited Adequacy and Insufficient for Grading as Low or High Grade: Outcome, Clinico-Pathological Correlates, and Predictive Role of p16INK4a and Ki67 Biomarker Staining

Moving forward-the 2019 ASCCP Risk-Based Management Consensus Guidelines for Abnormal Cervical Cancer Screening Tests and Cancer Precursors and beyond: implications and suggestions for laboratories

The 2019 ASCCP Risk Based Management Consensus Guidelines for prevention of cervical cancer promote clinical management recommendations aligned with our increased understanding of HPV biology and cervical carcinogenesis. They employ HPV-based testing as the basis for risk estimation, allow for personalized risk-based management by incorporating knowledge of current results with prior results, and streamline incorporation of new test methods as they are validated. They continue to support the principles of "equal management for equal risk" and "balancing harms and benefits" adopted in the 2012 version of the guidelines. These updated guidelines will be able to adjust for decreasing CIN3+ risks as more patients who received HPV vaccination reach screening age. Pathology organizations were closely involved in the development of these guidelines. Herein the pathologists who served as representatives to the 2019 ASCCP guidelines steering committee and workgroups, summarize the changes that are relevant to laboratories, pathologists, and cytotechnologists. Prior relevant screening and reporting recommendations that have not been widely and/or inconsistently adopted by laboratories are also discussed and considerations for modification of laboratory practices offered.

p16 Positive Histologically Bland Squamous Metaplasia of the Cervix: What does It Signify?

With increasing use of p16 immunohistochemistry (IHC) in diagnosis of premalignant lesions of cervix, we occasionally encounter p16 positivity in squamous metaplasia that lacks morphologic characteristics of "atypical squamous metaplasia" or of squamous intraepithelial lesion (SIL). Our study aims to investigate if transcriptionally active human papilloma virus (HPV) can be identified in such foci and if they have any relationship with squamo-columnar junction (SCJ) cells. Twenty-two cases of cervical specimens with at least a focus of p16 positive bland squamous metaplasia, were selected. HPV E6/E7 mRNA in situ hybridization followed by IHC for CK7 (SCJ biomarker), Ki67, and HPV16 E2, were performed. Follow-up information was obtained. Four cases were excluded due to insufficient tissue. Of the final 18 cases, HPV E6/E7 mRNA in situ hybridization was positive in all. Nine cases showed positivity in >50% cells and the epithelial thickness involved was ≥lower two-thirds in 13 cases. Of the further evaluable 15 cases, CK7 was positive in 14, Ki67 was positive in 10, and HPV16 E2 was negative in all. Concomitant high-grade squamous intraepithelial lesion was identified in 10 cases. On follow-up (duration: 1 to 19 mo), 6 patients showed histologic high-grade squamous intraepithelial lesion. Our study demonstrates that p16 positivity in squamous metaplasia of cervix is associated with the presence of transcriptionally active high-risk HPV even when there are no clear morphologic features of dysplasia. Our results suggest that these lesions are early SILs or SILs that are not yet morphologically evident, most of which arise from SCJ and should be closely followed.

Immunohistochemical Detection of p16 in Clinical Samples

P16 immunohistochemical expression, a surrogate marker of the retinoblastoma pathway, has become a major adjunct in the routine practice mostly of cervical and head/neck pathology, but with other indications too. In this chapter, a detailed immunohistochemical technique for the detection of p16 is described, followed by indications and interpretation of its expression in uterine, ovarian, vulvar, penile, head-and-neck, melanocytic, and other pathologies.