Diagnostic performance of fine needle aspiration cytology in the preoperative identification of mucoepidermoid carcinoma: a cross-sectional diagnostic analytical study

Background: Mucoepidermoid carcinoma (MEC), the most common malignant tumor of the salivary gland, accounts for 5%–10% of all salivary gland tumors. MEC shows extensive cytomorphological diversity, making preoperative diagnosis challenging. Hence, the present study was conducted to assess the diagnostic accuracy of fine-needle aspiration cytology (FNAC) in diagnosing MEC preoperatively and to discuss the cytological pitfalls in diagnosing mucoepidermoid carcinoma. Methods: The present study was a cross-sectional diagnostic analytical study conducted over a period of five years, which included confirmed cases of MEC. Each case was classified according to the Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) and individual cytomorphological features were noted. All cases were compared by considering histopathology as the gold standard for diagnosis. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of FNAC in diagnosing MEC were calculated to evaluate the diagnostic accuracy of FNAC. Results: All 42 cases of MEC were reclassified according to MSRSGC as follows: category II, one case; category III, one case; category IVA, two cases; category IVb, one case; category V, four cases; and category VI, 33 cases. Discordant cases (5 cases) were mainly due to cystic change, low cellularity, and overlapping features with benign lesions. The sensitivity, specificity, PPV, NPV, and diagnostic accuracy were found to be 88.1%, 100%, 100%, 97.4%, and 97.8%, respectively. Conclusions: FNAC is an important preoperative diagnostic investigation for MEC as reflected by its high specificity, sensitivity, and overall diagnostic accuracy in the present study. Careful attention to individual cytomorphological features and clinicoradiological correlation can significantly improve the diagnostic accuracy by directing the clinicians for further management.