Probes for P16

Oropharyngeal squamous cell carcinoma is frequently associated with high-risk HPV infection, which confers a good prognosis. Immunohistochemistry for p16 is used as a surrogate for HPV status, but discrepant results are occasionally seen. Here, we report a case with a unique pattern of partial loss of p16.A 63 year old male presented with a base of tongue nonkeratinizing squamous cell carcinoma and a large metastatic neck mass. The primary lesion and multiple regions of the metastatic mass were assessed with p16 immunohistochemistry, RNA in situ hybridization for high-risk HPV, and HPV16 genome sequencing.The primary lesion was p16 negative, and the metastatic neck mass had large, confluent regions that were either strongly p16 positive or entirely p16 negative. All of these regions were positive for high-risk HPV with identical HPV16 genomes.This unusual case illustrates a potential diagnostic pitfall, and it raises important questions regarding molecular mechanisms and prognostic implications of p16 staining in oropharyngeal squamous cell carcinoma.

Regarding a small proportion of oropharyngeal squamous cell carcinoma (OPSCC) patients who tested p16-positive but human papillomavirus (HPV)-negative, we attempted to perform HPV testing to improve the accuracy of HPV detection in OPSCC patients.We simultaneously performed Aptima HPV testing of cytological specimens and p16 immunohistochemistry (IHC) staining of histologic biopsies from the same cohort of patients with head and neck SCC (HNSCC). The cytological specimens included fine-needle aspiration specimens from patients with enlarged nodes and endoscopic brushing specimens from the primary lesions of patients without enlarged nodes. Cases with discordant results for p16 IHC staining and Aptima HPV testing were reexamined by a third method, RNAscope testing.Sixty patients with HNSCC (39 OPSCC and 21 non-OPSCC) were recruited for examination of HPV status. Among these patients, 28 were p16+/HPV+, 29 were p16-/HPV-, 2 were p16+/HPV-, and 1 was p16-/HPV+. The overall concordance rate between Aptima HPV testing and p16 IHC was 95.0%. Three cases with discordant results for these two methods were reexamined by RNAscope testing, and all were confirmed to be HPV negative. The prevalence of HPV in OPSCC and non-OPSCC patients was 61.5% (24/39) and 19.0% (4/21), respectively. The sensitivity and negative predictive values of Aptima HPV testing and p16 IHC were consistent at 100%, while the specificity and positive predictive values were 96.9% and 96.6% versus 93.8% and 93.3%, respectively. Additionally, 30 OPSCCs were simultaneously examined and diagnosed by both brush cytology and biopsy pathology; six of these SCCs were underdiagnosed by histopathology but accurately diagnosed by supplemental brush cytology.Aptima HPV testing of cytology specimens can be used as an adjuvant examination to identify false-positive OPSCC patients after p16 IHC of biopsies, while brush cytology may be a supplemental method for the histologic diagnosis of malignant oropharyngeal tumors.

Although both the 2014 and 2020 World Health Organization (WHO) criteria require unequivocal glandular and squamous differentiation for a diagnosis of cervical adenosquamous carcinoma (ASC), in practice, ASC diagnoses are often made in tumors that lack unequivocal squamous and/or glandular differentiation. Considering the ambiguous etiologic, morphologic, and clinical features and outcomes associated with ASCs, we sought to redefine these tumors. We reviewed slides from 59 initially diagnosed ASCs (including glassy cell carcinoma and related lesions) to confirm an ASC diagnosis only in the presence of unequivocal malignant glandular and squamous differentiation. Select cases underwent immunohistochemical profiling as well as human papillomavirus (HPV) testing by in situ hybridization. Of the 59 cases originally classified as ASCs, 34 retained their ASC diagnosis, 9 were reclassified as pure invasive stratified mucin-producing carcinomas, 10 as invasive stratified mucin-producing carcinomas with other components (such as HPV-associated mucinous, usual-type, or ASCs), and 4 as HPV-associated usual or mucinous adenocarcinomas with benign-appearing squamous metaplasia. Two glassy adenocarcinomas were reclassified as poorly differentiated HPV-associated carcinomas based on morphology and immunophenotype. There were no significant immunophenotypic differences between ASCs and pure invasive stratified mucin-producing carcinomas with regard to HPV and other markers including p16 expression. Although limited by a small sample size, survival outcomes seemed to be similar between all groups. ASCs should be diagnosed only in the presence of unequivocal malignant glandular and squamous differentiation. The 2 putative glassy cell carcinomas studied did not meet our criteria for ASC and categorizing them as such should be reconsidered.