Cytohistological correlation of salivary gland tumours with emphasis on Milan system for reporting: A novel step towards internal quality assurance

Abstract

Fine needle aspiration cytology (FNAC) is a cost-effective diagnostic technique for evaluation of salivary gland lesions. But, then, cytological evaluation of salivary gland lesions also has lot of challenges. To overcome the difficulties, “The Milan system for reporting salivary gland cytopathology” (MSRSGC) was introduced for diagnosis and management and establishing the risk of malignancy (ROM) in different categories. The present study was conducted to grade the salivary gland lesions according to Milan system of reporting and to correlate with their histopathological findings. The current study was conducted in the department of Pathology, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth, Pondicherry for a period of 5 years. Around 153 salivary gland lesions were aspirated. Salivary gland swellings were examined clinically, correlated with the details on the request forms and ultrasound findings, palpated and aspirated. The cytological features were evaluated and categorized according to Milan System for Reporting Salivary Gland Cytopathology”: Category 1: Nondiagnostic (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). They were further correlated with histopathological findings. All data were entered in MS excel sheet.Total 153 cases were evaluated cytologically, and histological followup was available in 134 cases. The distribution of cases into different categories were as follows Non-Diagnsotic (2.6%), Non-Neoplastic (20.9%), Atypia of Undetermined Significance (1.9%), Neoplastic-Benign (41.1%),Salivary gland neoplasm of Uncertain Malignant Potential (0%), Suspicious of Maligancy (0%) and Malignancy (33.3 %). Risk of malignancy were observed in categories 2 and 6 and were 3.84 % and 78.2 %. Sensitivity of FNAC in diagnosing salivary gland lesions was 84.2 %, specificity was 98.21%,positive predictive value was 94.64%, and negative predictive value was 91.70% with an accuracy of 93.60%.MSRSGC is a novel reporting system in cytological diagnosis of salivary gland lesions. Implementation of this reporting system in cytological diagnosis has enabled establishment of adequate diagnosis, assessment of risk stratification and facilitating clinicians to take further step in management plan.