Application of the Milan System for Reporting Salivary Gland Cytopathology: A 10-Year Experience in a Single Japanese Institution

Abstract

<b><i>Objective:</i></b> The Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) is a recently published evidence-based categorization system for salivary gland fine-needle aspiration (FNA). We applied MSRSGC to Japanese cases and evaluated its utility. <b><i>Study Design:</i></b> A total of 480 FNA cases were reviewed. We recategorized each case into one of the MSRSGC categories. The risk of neoplasm (RON) and the risk of malignancy (ROM) for each diagnostic category in MSRSGC, and the sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) for malignancy and for neoplasms were calculated for cases with histological follow-up. In addition, the overall ROM (O-ROM) was calculated for all FNA cases. <b><i>Results:</i></b> RON, ROM, and O-ROM rates were as follows – non-diagnostic: 51.3, 5.1, and 1.0%; non-neoplastic: 0, 0, and 0%; atypia of undetermined significance: 83.9, 12.9, and 7.3%; neoplasm, benign: 100, 0, and 0%; salivary gland neoplasm of uncertain malignant potential: 100, 32.1, and 23.7%; suspicious for malignancy: 100, 85.7, and 60%; and malignant: 100, 100, 81.8%. The sensitivity, specificity, and accuracy with (without) indeterminate cases for malignancy were 65 (100), 99 (99), 92% (99%) and PPV and NPV were 96 and 100%, respectively, and those for neoplasms were 84 (100), 100 (100), 85% (100%), and PPV and NPV were 100 and 100%, respectively. <b><i>Conclusions:</i></b> The MSRSGC is useful for stratification of ROM and for promoting the performance of salivary gland FNA. The MSRSGC could be easily introduced in Japan and may improve the Japanese salivary gland FNA status.

A multi‐institutional study of salivary gland cytopathology: Application of the Milan System for Reporting Salivary Gland Cytopathology in Japan

“…17 The sensitivity, specificity, accuracy, PPV, and NPV of the MSRSGC for diagnosing malignant lesions were as good as those described in previous studies. 11,14,[16][17][18][19] In the current study, there were 7 false-positive cases (see Supporting Table 2). One PA that was misdiagnosed as an acinic cell carcinoma showed cellular atypia with granular cytoplasm, enlarged nuclei, and conspicuous nucleoli.…”

“…[5][6][7] Use of the MSRSGC is currently spreading throughout the world, and many studies about its application in Asian countries, including Japan, have been published. [8][9][10][11] Salivary gland tumors are as uncommon in Japan, where they represent 6.1% of head and neck cancers and 0.2% of all malignancies, as they are in other countries; eg, they account for 6% of head and neck cancers and 0.3% of all malignancies in the United States. 12,13 Consequently, no large-scale studies of salivary gland FNAC have been conducted in Japan.…”

The Contributory Role of Cell Blocks in Salivary Gland Neoplasms Fine Needle Aspirations Classified by the Milan System for Reporting Salivary Gland Cytology

“…In a series of 6249 reviewed cases performed by the College of American Pathologists, the lymphoma cases featured the highest false-negative rate at 57% [33]. In recent MSRSGC analyses, 10 lymphoma cases were misinterpreted in a non-neoplastic category and 9 lymphoma cases in an AUS category [4,23,25,26,34].…”

“…The CBs in these cases were cellular, and either supported the neoplastic diagnosis or were crucial for the neoplastic diagnosis. To summarize other MSRSGC analyses, carcinoma ex PA cases were misinterpreted in a non-neoplastic category in three cases [6,23,35]: in an AUS category in one case [36] and in a SUMP category in only one case [4], but placement in a SUMP category is not generally rated as misinterpretation. Notably, nine cases were in a benign neoplasm IVA category [4,[23][24][25].…”

“…It aimed for better patient care, bringing a practical, evidence-based, user-friendly classification system with characterization and management algorithms [1,2]. Several international studies have stated that the MSRSGC is a reliable tool for salivary gland cytopathology categorization [3][4][5][6][7]. Cell blocks (CBs) are a collection of sediments and visible pieces of tissue from cytological specimens that are concentrated and processed into paraffin blocks, and stained with hematoxylin-eosinike surgical specimens.…”