Krane, Jeffrey F.

Context.— In 2018, an evidence-based guideline was published by the College of American Pathologists to develop recommendations for the testing, application, interpretation, and reporting of high-risk human papillomavirus and surrogate marker tests in head and neck carcinomas. Substantial new evidence has prompted a review, including data on human papillomavirus (HPV) in nonoropharyngeal anatomic sites, HPV global rates, p16 immunohistochemistry, and HPV testing performance in cytology specimens, and performance of p16 immunohistochemistry as a surrogate marker. Objective.— To assess research published since the release of the original 2018 guideline and to update evidence-based recommendations for HPV testing in head and neck carcinomas. Design.— The College of American Pathologists convened a panel of experts to update the guideline following the standards established by the National Academy of Medicine for developing trustworthy clinical practice guidelines. The expert panel defined the key questions and performed a systematic review of the literature. Using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, recommendations were updated on the basis of available evidence, certainty of that evidence, and key judgments. Results.— Seven strong recommendations, 4 conditional recommendations, and 5 good practice statements are offered in the guideline update. Conclusions.— The updated guideline statements provide direction on the nature of HPV testing in various head and neck specimens (including key updates based on new research on sinonasal squamous cell carcinoma) and expanded guidance on specific scenarios and practice settings. The goal is to improve and standardize, where possible, HPV testing across diverse pathology practice settings and different countries.

BackgroundFine needle aspiration (FNA) is commonly used for the preoperative evaluation of salivary gland tumors. Tumor grade is a key factor influencing clinical management of salivary gland carcinomas (SGCs). To assess the ability to grade nonbasaloid SGCs in FNA specimens, an international panel of cytopathologists convened to review and score SGC cases.MethodsThe study cohort included 61 cases of primary SGC from the pathology archives of 3 tertiary medical centers. Cases from 2005 to 2016 were selected, scanned, and digitized. Nineteen cytopathologists blinded to the histologic diagnosis reviewed the digitized cytology slides and graded them as low, high, or indeterminate. The panelists' results were then compared to the tumor grades based on histopathologic examination of the corresponding resection specimens.ResultsAll but 2 of the 19 (89.5%) expert panelists review more than 20 salivary gland FNAs per year; 16 (84.2%) of the panelists work at academic medical centers, and 13 (68.4%) have more than 10 years' experience. Participants had an overall accuracy of 89.4% in the grading of SGC cases, with 90.2% and 88.3% for low‐ and high‐grade SGC, respectively. Acinic cell carcinoma and mucoepidermoid carcinoma had the highest degree of accuracy, while epithelial‐myoepithelial carcinoma and salivary duct carcinoma had the lowest degree of accuracy. As expected, the intermediate‐grade SGC cases showed the greatest variability (high‐grade, 42.1%; low‐grade, 37.5%, indeterminate, 20.4%).ConclusionThis study confirms the high accuracy of cytomorphologic grading of primary SGC by FNA as low‐ or high‐grade. However, caution should be exercised when a grade cannot be confidently assigned.

NOTCH1 is frequently mutated in adenoid cystic carcinoma (ACC). To test the idea that immunohistochemical (IHC) staining can identify ACCs with NOTCH1 mutations, we performed IHC for activated NOTCH1 (NICD1) in 197 cases diagnosed as ACC from 173 patients. NICD1 staining was positive in 194 cases (98%) in 2 major patterns: subset positivity, which correlated with tubular/cribriform histology; and diffuse positivity, which correlated with a solid histology. To determine the relationship between NICD1 staining and NOTCH1 mutational status, targeted exome sequencing data were obtained on 14 diffusely NICD1-positive ACC specimens from 11 patients and 15 subset NICD1-positive ACC specimens from 15 patients. This revealed NOTCH1 gain-of-function mutations in 11 of 14 diffusely NICD1-positive ACC specimens, whereas all subset-positive tumors had wild-type NOTCH1 alleles. Notably, tumors with diffuse NICD1 positivity were associated with significantly worse outcomes (P=0.003). To determine whether NOTCH1 activation is unique among tumors included in the differential diagnosis with ACC, we performed NICD1 IHC on a cohort of diverse salivary gland and head and neck tumors. High fractions of each of these tumor types were positive for NICD1 in a subset of cells, particularly in basaloid squamous cell carcinomas; however, sequencing of basaloid squamous cell carcinomas failed to identify NOTCH1 mutations. These findings indicate that diffuse NICD1 positivity in ACC correlates with solid growth pattern, the presence of NOTCH1 gain-of-function mutations, and unfavorable outcome, and suggest that staining for NICD1 can be helpful in distinguishing ACC with solid growth patterns from other salivary gland and head and neck tumors.