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

Abstract

Salivary gland masses are often encountered in the everyday practice of cytopathology. It is commonly known that the cytologic interpretation of these lesions can pose diagnostic problems due to overlapping cytomorphologic features. Fine needle aspiration (FNA) of salivary lesions shows good to excellent sensitivity and specificity in differentiating a neoplastic from a non-neoplastic process and in diagnosing common tumors such as pleomorphic adenoma. However, its value is limited in diagnosing specific neoplastic entities especially those with well-differentiated morphology. In light of this gap, an international group of pathologists has proposed a management-oriented, tiered classification for reporting salivary gland FNA specimens, “The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC)”. Similar to other classification systems, the MSRSGC scheme comprises six diagnostic categories, which were linked with a specific risk of malignancy (ROM) and management. In this review article, the author evaluated the published literature on FNA in diagnosing salivary gland lesions with the adoption of the Milan system since its introduction in the daily practice of salivary cytopathology.

Utility of the Milan System for Reporting Salivary Gland Cytology, with focus on the incidence and histologic correlates of atypia of undetermined significance (AUS) and salivary gland neoplasm of uncertain malignant potential (SUMP): A 3‐year institutional experience

“…10,15 According to Rossi et al, some of the limitations of the MSRSGC will be on the forefront of discussions and revisions in the upcoming second edition of the MSRSGC, which is anticipated for the fall of 2022. 24 The ROM for the 6 MSRSGC diagnostic categories reported in the literature shows a wide range, from 0% to 50% for ND, 0% t o33.3% for NN, 0% to 100% for AUS, 0% to 18.8% for BN, 14% to 100% for SUMP, 50% to 100% for SFM, and 87.5% to 100% for malignant. Our results indicate ROMs comparable to those reported in literature, with a sensitivity and specificity of 100%.…”

“…According to Rossi et al, some of the limitations of the MSRSGC will be on the forefront of discussions and revisions in the upcoming second edition of the MSRSGC, which is anticipated for the fall of 2022 24 …”

Salivary gland neoplasms with basaloid features in the era of the Milan system for reporting salivary gland cytology: Classification and interobserver agreement

“…Calculated sensitivity and specificity for basaloid neoplasm classification were 90% and 91% respectively. Published data for the MSRSGC analyzing unselected populations of salivary gland lesions show sensitivities varying from 72% to 95% 18–20 . The specificity ranged from 78% to 100% 18–20 These ranges for sensitivity and specificity overlap suggesting that the MSRSGC when used for classifying basaloid neoplasms is as accurate as when classifying salivary gland neoplasms in general.…”

“…Predictive values of a negative test and of a positive test were also high being 92% and 90% respectively. Data from these studies suggest that the indeterminant category of SUMP aids in maintaining the high diagnostic accuracy of the MSRSGC even for basaloid neoplasms by placing especially diagnostically difficult lesions in this indeterminate category 18–20 …”

“…Published data for the MSRSGC analyzing unselected populations of salivary gland lesions show sensitivities varying from 72% to 95%. [18][19][20] The specificity ranged from 78% to 100% [18][19][20] These ranges for sensitivity and specificity overlap suggesting that the MSRSGC when used for classifying basaloid neoplasms is as accurate as when classifying salivary gland neoplasms in general. Predictive values of a negative test and of a positive test were also high being 92% and 90% respectively.…”