Background: In 2018, the Milan System for Reporting Salivary Gland Cytopathology was published defining a diagnostic categorization scheme with known malignancy risks and clinical follow up recommendations. Inter-observer reproducibility of the categories was not defined.Methods: Salivary gland fine-needle aspirations (FNA) were reviewed over a 5 year period and classified by three independent observers. Inter-observer reproducibility was estimated using observed agreement and chance corrected agreement (Cohen's kappa).Results: Four hundred and eight cases were reviewed with chance corrected agreement of 0.42 for the original Milan System and 0.48 for a modified system using "similar follow up" categories. Categories 4A and 6B showed substantial agreement (kappa =0.71 and 0.72).Conclusion: The Milan System shows moderate over all agreement between observers. Strongest inter-observer agreement was seen for categories 4A and 6B. K E Y W O R D Scytopathology, inter-observer reproducibility, Milan system, salivary gland

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: A number of guidelines have been developed to improve standardization of the terminology and criteria for cytologic specimens obtained from the thyroid, pancreas, lung, and salivary glands. A major goal of these guidelines is to improve reproducibility and understanding of the reporting of diagnostic results among cytopathologists and between cytopathologists and clinicians. The International Academy of Cytology Yokohama System for Reporting Breast Fine-Needle Aspiration Biopsy Cytopathology (IAC YSRB) is the most recent of these guidelines. The value of this system is, in part, dependent upon interobserver reproducibility. Design: Ninety consecutive fine-needle aspiration biopsies (FNAB) of the breast, performed over a 6-year period, were independently evaluated by 4 board-certified pathologists blinded to the original diagnoses. The 5 diagnostic categories used were those of the IAC YSRB according to published criteria for these categories. Observed agreement and chance corrected agreement (Fliess κ) were calculated. Differences in κ values were evaluated using the T statistic of Gwent. Statistical calculations were performed using STATA v16.0 (STATA Corp., College Station, TX, USA). Results: Overall agreement between observers was good. Observed unweighted agreement was 69% and weighted agreement was 91%. The majority of diagnoses were concordant (68.6%). Conclusions: Interobserver agreement of 4 cytopathologists was good using the 5 categories of the IAC YRSB (69%). Agreement was greater among pathologists with more years of experience. The IAC YSRB system appears to provide greater agreement among viewers than guidelines for cytologic specimens obtained from some other body sites (salivary gland and lung). Most discrepancies were only by a single category, with only 22/113 (19%) differing by more than one category.

Background: A number of categorization systems had been developed for the reporting of cytology specimens with the aim of providing uniform definitions, criteria, and diagnostic terminology. The intention of these systems is to improve reproducibility of diagnostic categorization with standardized estimates of malignancy risk. Required for the success of these systems is a high level of interobserver reproducibility for category assignment. Recently, the international system for serous fluid cytopathology (TIS) was proposed using the categories nondiagnostic, negative for malignancy, atypia of undetermined significance (AUS), suspicious for malignancy, and malignant. Little data exists documenting the interobserver agreement for these categories.Design: A search of the cytology records at the University of Missouri was performed for all pleural fluid specimens obtained between January 2014 and December 2019.A total of 200 specimens were reviewed independently by three board-certified cytopathologists. Specimens were characterized as nondiagnostic, negative, AUS, suspicious for malignancy, and malignant. Interobserver agreement was analyzed using Cohen's kappa.Results: Overall observer agreement was 68% and chance-corrected weighted agreement (weighted kappa) was 0.63. Agreement was good for categories negative and malignant, but poor for categories atypia of uncertain significance, and suspicious for malignancy. Conclusions:The TIS has performance characteristics similar to other cytologic classification schemes. Interobserver agreement is best for the negative (76%) and malignant (81%) categories. Interobserver agreement is poor for the category's AUS, and suspicious for malignancy. This is similar to interobserver agreement associated with other published categorization systems.