Application of the milan system for reporting salivary gland cytology and risk stratification by cytohistological correlation

Abstract

Introduction: Salivary gland neoplasms are uncommon tumors comprising <3%–10% of all head-and-neck neoplasms. Recent WHO classification of salivary gland tumor added many newer entities; however, no definite risk-stratification system is specified to predict the likelihood of malignancy for each diagnostic category. The present study is designed to evaluate the salivary gland aspirates using the Milan System for Reporting Salivary Gland Cytology for reporting correlating with histological diagnosis which will lead to determine the malignancy risk for each diagnostic category. Risk of malignancy is calculated by the ratio of cytopathology cases with a malignant histopathology to the total number of cytopathology cases with follow-up histopathology for that particular category. Materials and Methods: The present study was a cross-sectional study done prospectively over a period of 2 years, and a total of 72 participants were selected. This study characterized the cytological features of spectrum of salivary gland lesions varying from benign to malignant. The lesions were evaluated and classified cytologically according to “the Milan System for Reporting Salivary Gland Cytopathology” for reporting salivary gland neoplasms. Histopathological correlation was done with cytological diagnosis wherever possible. Results: In our study of 72 patients with salivary gland lesions with the mean age of the patient being 50.6 years and maximum number of lesions involved the parotid gland followed by the submandibular gland and sublingual gland. Majority of the lesions in the present study were nonneoplastic in nature followed by lesions benign in nature. Malignant lesions were least common in occurrence. Among 72 cases, majority of the cases were seen in Milan category II (nonneoplastic) consisting of 34 cases (47.2%), followed by 31 cases (43.1%) in Milan category IV (benign). Final diagnostic categorization of 72 cases of salivary gland lesions was done according to the Milan system and the histopathological correlation was available in 23 of these cases. Out of the 34 cases in Milan system category II (nonneoplastic), histopathological evaluation was done in 2 cases. Both the cases were benign in nature, 31 cases in Milan system category IV (benign) histopathological evaluation was done in 16 cases where 15 cases were benign in nature and 1 lesion was malignant. Four cases were put in category VI of the Milan system, histopathological evaluation was done in all the 4 cases which were all malignant in nature. Conclusion: The current study validates fine-needle aspiration cytology as a cost-effective and noninvasive procedure for differentiating between benign and malignant lesions of the salivary gland, information of critical importance when determining the patient's next course of treatment.