Diagnostic Performance of the Milan System for Reporting Salivary Gland Cytopathology and a Proposed Algorithm for Fine-Needle Aspiration Cytology of Salivary Gland Lesions

Introduction: We evaluated concordance between Milan System for Reporting Salivary Gland Cytopathology (MSRSGC)-based categorization of salivary gland masses/lesions screened by fine-needle aspiration cytology (FNAC) and final histopathologic diagnoses, aiming to identify factors predictive of concordance, with the goal of appropriate case management. Methods: The study was retrospective and involved 101 cases of salivary mass/lesion examined by FNAC. We compared MSRSGC categories against the final histopathologic classes (non-neoplasm, benign neoplasm, or malignant neoplasm) and calculated diagnostic concordance in each class. Concordance was defined as: MSRSGC categorization of a lesion as a category II lesion and a histopathologic classification as a non-neoplasm; MSRSGC categorization of a lesion as a category IV-A lesion and a histopathologic classification as a benign neoplasm; or MSRSGC categorization of a lesion as a category V or VI lesion and a histopathologic classification as a malignant neoplasm. We then compared clinicopathologic factors between concordant and discordant cases. Results: Diagnostic concordance for non-neoplasms, benign neoplasms, malignant neoplasms, and total cases was 81.8% (9/11), 81.7% (58/71), 66.6% (8/12), and 79.8% (75/94), respectively, with no significant between-class difference. We found the shortest distance from the body surface to the salivary lesion differed significantly between the concordant group and the discordant group (5.35 mm vs. 7.30 mm), and the optimal cutoff was determined to be 8.00 mm (p < 0.01). Conclusion: Based on the distance of either <8 mm or >= 8 mm from the body surface to the mass/lesion, we believe our proposed FNAC algorithm of treatment strategies is a reliable guide for otolaryngologists on evaluating salivary gland lesions.