Enhancing Diagnostic Precision and Clinical Outcomes With FNAC in Parotid Gland Masses

Background: Parotid gland masses encompassing both neoplastic and non-neoplastic conditions present diagnostic challenges. Fine-needle aspiration cytology (FNAC) is commonly used to differentiate between benign and malignant lesions but has limitations such as variable sensitivity and potential sampling errors. This study assesses FNAC's accuracy for parotid gland lesions, evaluates the Milan Salivary Gland Cytopathology Reporting System (MSRSGC), and compares FNAC results with histopathological findings.

Methods: This retrospective study at our medical center analyzed data from 2321 patients who underwent parotid gland FNAC followed by surgical resection over 20 years. Patients were included if they had both cytological analysis and surgery between January 2004 and July 2024. Surgical procedures varied based on mass characteristics and FNAC results, and all samples were assessed using MSRSGC. Statistical analysis compared FNAC results with histopathology findings, calculating sensitivity, specificity, and accuracy.

Results: This study included 352 patients who underwent both FNAC and surgical resection. FNAC had an overall accuracy of 93.9%, with a sensitivity of 78.3% and specificity of 91.5%. The risk of malignancy was 30% for Milan Category I (nondiagnostic), 6.3% for Category II (non-neoplastic), 0% for Category III (Atypia of Undetermined Significance), 2.3% for Category IVa (benign neoplasm), 5.8% for Category IVb (neoplasm of uncertain malignant potential), 58.8% for Category V (suspicious for malignancy), and 95% for Category VI (malignant). The false negative rate was 2.4%, while the false positive rate was 3.4%. The malignancy risk increased with age, and malignant masses were larger and more likely to cause facial paralysis.

Conclusion: FNAC is a key diagnostic tool for parotid gland masses, offering high specificity and accuracy despite some limitations. Patients with young ages and inappropriate histories should be assessed more carefully. MSRSGC is a useful system to show appropriate risk of malignancy.