Cystic salivary gland lesions present diagnostic challenges on fine-needle aspiration (FNA) specimens that are related to sampling limitations and a broad differential diagnosis. This study evaluated the benefit of applying the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) to a series of cystic salivary gland lesions.
The pathology archives at the Johns Hopkins Hospital were searched to identify cystic salivary gland FNA specimens over a 19-year period (2000-2018). Patient demographics, cytomorphologic features, and clinical and surgical follow-up were recorded. The MSRSGC was applied to the cases. The risk of malignancy (ROM) and the risk of neoplasia (RON) were calculated for each category.
One hundred seventy-eight cases were identified (96 males and 82 females) with a mean age of 53 years (range, 4-90 years). After the MSRSGC was applied, there were 52 nondiagnostic cases (29.2%), 80 nonneoplastic cases (44.9%), 35 cases of atypia of undetermined significance (AUS; 19.7%), 3 benign neoplasms (1.7%), 3 salivary gland neoplasms of uncertain malignant potential (SUMP; 1.7%), 4 cases suspicious for malignancy (SFM; 2.2%), and 1 malignant case (0.6%). One hundred fifty-six of the 178 patients (87.6%) had follow-up data available. The RON and ROM values for cases with surgical follow-up were 33.3% (3 of 9) and 22.2% (2 of 9) for the nondiagnostic category, 42.9% (9 of 21) and 19% (4 of 21) for the nonneoplastic category, 76.5% (13 of 17) and 29.4% (5 of 17) for the AUS category, 100.0% (2 of 2) and 50.0% (1 of 2) for the SUMP category, and 100% (2 of 2) and 100% (2 of 2) for the SFM category, respectively.
Applying the MSRSGC to cystic salivary gland lesions improves patient management by preventing unnecessary surgery for nonneoplastic conditions. The ROM was highest in the SFM category (100%), which was followed by the SUMP, AUS, nondiagnostic, and nonneoplastic categories. Less than adequate specimens may increase the diagnosis of AUS.

BACKGROUND: The use of fine-needle aspiration (FNA) cytology for the preoperative evaluation of salivary gland lesions is an accepted but, currently, nonstandardized practice. More specifically, cystic major salivary gland lesions are relatively rare and can be very challenging to diagnose on FNA due to low cellularity and an incredibly broad differential diagnosis. The purpose of this study was to investigate the diagnostic utility of preoperative FNA cytology for cystic major salivary gland lesions.
METHODS: The electronic pathology archives of The Johns Hopkins Hospital were searched to identify FNA specimens of cystic major salivary gland lesions over a 15 year period (January 1, 2000 to December 21, 2015). The age, race, sex, biopsy site, use of ultrasound guidance, cytopathologic diagnosis, and presence or absence of clinical follow-up were recorded for each patient. Cases were divided into those with and without follow-up. Diagnostic performance between FNA and follow-up data were recorded.
RESULTS: A total of 145 cases met the inclusion criteria, while 123 (84.8%) patients had follow-up data available. Of these patients, 67.5% underwent FNA as the only pathologic diagnostic modality. Sensitivity, specificity, positive predictive value, and negative predictive value for the detection of cystic neoplasms were 41.6%, 99.0%, 90.9%, and 87.6%, respectively. For cases containing mucin, 100.0% sensitivity and specificity were achieved.
CONCLUSIONS: FNA of cystic salivary gland lesions is a useful clinical decision-making tool that can reduce the number of patients ultimately requiring surgical excision. Although specificity is high, a relatively low overall sensitivity makes clinical and radiologic correlation imperative.