Cytological Study of Salivary Gland Lesions in Accordance with the Milan System of Reporting Salivary Gland Cytopathology

Aim: Fine needle aspiration cytology is an essential diagnostic tool for preoperative diagnosis of salivary gland lesions. Due to overlapping cytological features and heterogenecity of the lesions, a universal classification system was proposed, known as the “Milan System of Reporting Salivary Gland Cytopathology (MSRSGC). This system helps clinicians to plan further diagnosis and management according to the risk of malignancy (ROM) in different categories. Therefore, the aim was to stratify the lesions according to the system and calculate the risk of malignancy.

Study Design: Retrospective and prospective study.

Place and Duration of Study: Department of Pathology, Dr.D.Y.Patil Medical College, Hospital and Research Centre, Pune, between August 2016 and July 2021.

Methodology: A five year study was conducted on 100 cases. FNAC was performed and correlation to histopathological aspects of resected and/or biopsied lesions were carried out in which tissue specimens were available. The cytological diagnosis was re-evaluated as follows: Category 1: Non‑diagnostic (ND), Category 2: Non‑neoplastic (NN), Category 3: Atypia of undetermined significance (AUS), Category 4a: Neoplasm: Benign (NB),Category 4b: Neoplasm: Salivary gland neoplasm of uncertain malignant potential (SUMP),Category 5: Suspicious of malignancy (SM) and Category 6: Malignant (M).

Results: Total 100 cases were studied. Histopathology reassessment was available in 38 cases. Case distribution in various categories were ND (0%), NN(36%), AUS(3%), NB(54%), SUMP(1%), SM(3%) and M(3%). Overall ROM reported were 0%, 11.11%, 100%, 0%, 100%, 100% and 100% respectively for each category. The diagnostic accuracy, sensitivity, specificity, positive predictive value and negative predictive value of the study was 94.74%, 75%, 100%, 100% and 100% respectively.

Conclusion: The Milan system is an universal 6-tier reporting system of lesions of salivary gland that helps with risk assessment and guides the clinicians for appropriate treatment.