Salivary gland fine‐needle aspiration cytology with the application of the Milan system for risk stratification and histological correlation: A retrospective 6‐year study

Abstract

Background: The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is based on risk stratification. We presented our experience with fineneedle aspiration cytology (FNAC) for the diagnosis of salivary glands lesions by applying the MSRSGC categorization to the cytological diagnoses, and determined risk of malignancy (ROM) for each category. Methods: Fine-needle aspiration cytology of salivary gland lesions performed over a 6-year period was retrieved. FNAC results were retrospectively categorized according to the MSRSGC criteria, and correlated with corresponding histologic follow-up. ROM for each diagnostic category was calculated. Results: A total of 208 FNAC of salivary gland lesions were reviewed and retrospectively categorized as: non-diagnostic (ND) 23 (11%), non-neoplastic (NN) 54 (26%), atypia of undetermined significance (AUS) 10 (4.8%), benign neoplasms (BN) 77 (37%), salivary gland of uncertain malignant potential (SUMP) 13 (6.3%), suspicious for malignancy (SM) 7 (3.4%), and malignant (M) 24 (11.5%). Histopathological follow-up was available for 84 of 208 cases (40.4%). Overall concordance rate between FNAC and histology was 78.8%. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated as 93.3%, 94.6%, 82.4%, and 98.2%, respectively. Diagnostic accuracy to distinguish benign from malignant disease was 94.4%. ROM for each category was ND 0%, NN 0%, AUS 75%, BN 2.2%, SUMP 28.6%, SM 50%, and M 100%. Conclusion: Fine-needle aspiration cytology continues to be an accurate diagnostic tool for most salivary gland neoplasms showing classical morphologic features. However, difficult cases with unusual or overlapping features will occur. In these situations, the use of MSRSGC risk-stratification could be helpful to define appropriate management.

The Milan System, from Its Introduction to Its Current Adoption in the Diagnosis of Salivary Gland Cytology

“…The use of cytology confirmed its relevant role as for a 94.4% diagnostic accuracy in discriminating benign from malignant neoplasms. Moreover, their result confirmed that the ROM for each category was perfectly in line with the MSRSGC ROM in each diagnostic category [49].…”

“…The data from 2018 and 2019 were confirmed in 2020 with the publication of different papers confirming the useful role of the MSRSGC system [20][21][22][23][24][25]27,[46][47][48][49][50].…”

“…A series of 208 SG-FNAC cases, performed over a 6-year period, were re-classified according to the Milan system by Rivera-Rolon et al [49]. The yields confirmed that the overall concordance rate between SG-FNAC and histology was 78.8%.…”

Milan system for reporting salivary gland cytopathology: Adoption and outcomes in a community setting

“…These categories have been validated by multiple retrospective reviews of cytopathology reports across the globe since the introduction of the MSRSGC in 2015. [6][7][8] Viswanathan et al in 2018 performed a retrospective analysis of 627 salivary gland FNAs applying the MSRSGC and found strong correlation between the proposed risk of malignancy and the actual rate of malignancy after sialoadenectomy. 9 Rivera Rolon et al reviewed 208 salivary gland FNAs in 2020 that confirmed these findings and suggested a diagnostic accuracy of 94.4% when distinguishing benign versus malignant pathology.…”

“…The observed rate of malignancy in our dataset is similar to the proposed risk of malignancy by the MSRSGC. These categories have been validated by multiple retrospective reviews of cytopathology reports across the globe since the introduction of the MSRSGC in 2015 6–8 . Viswanathan et al in 2018 performed a retrospective analysis of 627 salivary gland FNAs applying the MSRSGC and found strong correlation between the proposed risk of malignancy and the actual rate of malignancy after sialoadenectomy 9 .…”