Background Fine‐needle aspiration (FNA) of a neck mass is frequently the initial diagnostic procedure for patients with human papillomavirus–positive head and neck squamous cell carcinoma. By performing a p16 immunocytochemistry (ICC) stain on FNA material, the pathologist can help to direct the treating physician's search for the primary site and to select the proper management for the patient. There is currently no established threshold for the evaluation of p16 ICC in cytology samples. This study was aimed at establishing an optimal threshold for p16 ICC interpretation in cytology samples. Methods The pathology databases were searched for all neck‐mass FNAs diagnosed as squamous cell carcinoma from January 2010 to March 2019. p16 ICC was performed on cytology smears, and the percentage and intensity of p16‐positive cells were assessed. Receiver operating characteristic (ROC) curves were plotted to determine the best cutoff threshold for p16 positivity on cytology smears. Results p16 ICC was performed on 50 cytology smears. An analysis of 8 different thresholds (combinations of the percentage and intensity of the p16 stain) using ROC curves demonstrated the best threshold to be 50% p16 staining with a sensitivity of 74% and a specificity of 100%. Applying the threshold used for surgical specimens (70%) to cytology samples resulted in a low sensitivity (45%). Conclusions p16 ICC on cytology smears shows diminished staining in comparison with surgical samples. Using 50% staining as the cutoff to consider positivity for p16 in cytology smears is proposed to decrease false‐negative results while maintaining specificity.
Background Oral squamous cell carcinoma (OSCC) has poor survival rates. There is a pressing need to develop more precise risk assessment methods to tailor clinical treatment. Epigenome-wide association studies in OSCC have not produced a viable biomarker. These studies have relied on methylation array platforms, which are limited in their ability to profile the methylome. In this study, we use MethylCap-Seq (MC-Seq), a comprehensive methylation quantification technique, and brush swab samples, to develop a noninvasive, readily translatable approach to profile the methylome in OSCC patients. Methods Three OSCC patients underwent collection of cancer and contralateral normal tissue and brush swab biopsies, totaling 4 samples for each patient. Epigenome-wide DNA methylation quantification was performed using the SureSelectXT Methyl-Seq platform. DNA quality and methylation site resolution were compared between brush swab and tissue samples. Correlation and methylation value difference were determined for brush swabs vs. tissues for each respective patient and site (i.e., cancer or normal). Correlations were calculated between cancer and normal tissues and brush swab samples for each patient to determine the robustness of DNA methylation marks using brush swabs in clinical biomarker studies. Results There were no significant differences in DNA yield between tissue and brush swab samples. Mapping efficiency exceeded 90% across all samples, with no differences between tissue and brush swabs. The average number of CpG sites with at least 10x depth of coverage was 2,716,674 for brush swabs and 2,903,261 for tissues. Matched tissue and brush swabs had excellent correlation (r = 0.913 for cancer samples and r = 0.951 for normal samples). The methylation profile of the top 1000 CpGs was significantly different between cancer and normal samples (mean p-value = 0.00021) but not different between tissues and brush swabs (mean p-value = 0.11). Conclusions Our results demonstrate that MC-Seq is an efficient platform for epigenome profiling in cancer biomarker studies, with broader methylome coverage than array-based platforms. Brush swab biopsy provides adequate DNA yield for MC-Seq, and taken together, our findings set the stage for development of a non-invasive methylome quantification technique for oral cancer with high translational potential.
Aims Current available data on cytokeratin 7 (CK7) immunostaining pattern in the clear cell renal cell carcinoma (RCC) spectrum is conflicting. The aim of this study was to assess CK7 immunoreactivity within the spectrum of clear cell renal neoplasms, including clear cell RCC, multicystic renal neoplasm of low malignant potential and clear cell papillary RCC‐like tumours. Methods and results We analysed two clones of CK7 and two tumour blocks for a total of 75 cases divided into five distinct groups: (i) low‐grade clear cell RCC, (ii) high‐grade clear cell RCC, (iii) multicystic renal neoplasm of low malignant potential, (iv) clear cell RCC with cystic changes and (v) clear cell papillary RCC‐like tumours. We found the highest CK7 reactivity in low‐grade clear cell RCC, multicystic renal neoplasm of low malignant potential and clear cell papillary RCC‐like groups, ranging from 60% to 93%. Conclusions Our findings show that CK7 immunoreactivity in clear cell RCC is variable, and the extent of staining depends on the grade and architectural growth patterns of the tumours.
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