Role of the Biomarker p16 in Downgrading -IN 2 Diagnoses and Predicting Higher-grade Lesions

Am J Surg Pathol. 2015 Dec;39(12):1708-18. doi: 10.1097/PAS.0000000000000494.

Abstract

In 2012, the College of American Pathologists and American Society for Colposcopy and Cervical Pathology published the "LAST" recommendations for histopathology reporting of human papilloma virus-related squamous lesions of the lower anogenital tract, including the use of a 2-tier nomenclature (low-grade squamous intraepithelial lesion/high-grade squamous intraepithelial lesion [LSIL/HSIL]) and expanded use of the biomarker p16 to classify equivocal lesions as either precancer (HSIL) or low-grade lesions (LSIL)/non-human papilloma virus changes. We aimed to determine (1) the frequency with which the poorly reproducible diagnosis of intermediate-grade (-IN 2) lesion in the lower anogenital tract would be downgraded on the basis of p16 results, and (2) whether p16 status was predictive of subsequent higher-grade lesions. A total of 200 specimens diagnosed as an intermediate-grade (-IN 2) lesion of the cervix (168), vagina (2), vulva (2), and anus (28) were reviewed and immunostained for p16. Slides were independently reviewed by 2 pathologists, with discrepant p16 interpretations adjudicated by a third pathologist. Of the 200 cases, 32% were negative for p16. Among the 166 patients with subsequent pathology (including 131 excisions), 26.2% of p16-positive cases versus 4.4% of p16-negative cases were associated with a subsequent diagnosis of HSIL (-IN 3) or worse (P=0.002). Reproducibility of the biopsy diagnosis was fair, with no significant difference with the addition of p16 or using 2 versus 3 tiers. In 11.5% of cases, there was discordance in p16 interpretation (κ 0.735, good agreement). The results indicate that using the Lower Anogenital Squamous Terminology recommendations would result in approximately one third of equivocal (-IN 2) diagnoses being downgraded to LSIL over 1 year in a busy academic practice. The significant association of p16 expression with a higher risk for HSIL on a subsequent specimen suggests that use of p16 to adjudicate equivocal (-IN 2) diagnoses in lower anogenital tract specimens as either LSIL or HSIL would likely predict lesion grade more accurately and avoid unnecessary excisional procedures.

MeSH terms

  • Adult
  • Aged
  • Anus Neoplasms / chemistry*
  • Anus Neoplasms / pathology
  • Anus Neoplasms / therapy
  • Anus Neoplasms / virology
  • Biomarkers, Tumor / analysis*
  • Biopsy
  • Cyclin-Dependent Kinase Inhibitor p16 / analysis*
  • Female
  • Humans
  • Immunohistochemistry
  • Male
  • Middle Aged
  • Neoplasm Grading
  • Observer Variation
  • Papillomavirus Infections / virology
  • Predictive Value of Tests
  • Reproducibility of Results
  • Squamous Intraepithelial Lesions of the Cervix / metabolism*
  • Squamous Intraepithelial Lesions of the Cervix / pathology
  • Squamous Intraepithelial Lesions of the Cervix / therapy
  • Squamous Intraepithelial Lesions of the Cervix / virology
  • Uterine Cervical Dysplasia / chemistry*
  • Uterine Cervical Dysplasia / pathology
  • Uterine Cervical Dysplasia / therapy
  • Uterine Cervical Dysplasia / virology
  • Uterine Cervical Neoplasms / chemistry*
  • Uterine Cervical Neoplasms / pathology
  • Uterine Cervical Neoplasms / therapy
  • Uterine Cervical Neoplasms / virology
  • Vaginal Neoplasms / chemistry*
  • Vaginal Neoplasms / pathology
  • Vaginal Neoplasms / therapy
  • Vaginal Neoplasms / virology
  • Vulvar Neoplasms / chemistry*
  • Vulvar Neoplasms / pathology
  • Vulvar Neoplasms / therapy
  • Vulvar Neoplasms / virology
  • Young Adult

Substances

  • Biomarkers, Tumor
  • Cyclin-Dependent Kinase Inhibitor p16