Objectives: Fine needle aspiration cytology (FNAC) has been employed in pre-operative diagnosis of salivary gland lesions for many years. Various studies in the existing literature have shown a wide range of sensitivity and diagnostic accuracy of cytologic diagnosis. This study was aimed at evaluating salivary gland FNAC for sensitivity, specificity and diagnostic accuracy at a tertiary care center.
Materials and methods: This study included 80 patients who underwent pre-operative FNAC followed by surgical procedure and histologic examination. The histologic diagnosis was considered as the gold standard. FNAC diagnosis was compared with the final histologic impression and concordance assessed. Sensitivity, specificity and diagnostic accuracy of FNAC for malignant lesions were calculated.
Results: Of the 80 cases, majority (67.5%) involved the parotid gland. Eight cases (10%) were non-neoplastic lesions, comprised of sialadenitis, retention cyst and sialadenosis. Of a total of 72 neoplasms, 58 were benign and 14 were malignant salivary gland tumors. A cyto-histologic concordance of benign diagnosis was achieved in 85.7% of cases and for malignant lesions in 92.8% of the malignant tumors. FNAC showed a sensitivity of 92.8%, specificity of 93.9%, a positive predictive value of 81.2% and negative predictive value of 98.4% for malignant salivary gland tumors. There was one false-negative diagnosis and four false-positive cases diagnosed on FNAC.
Conclusion: FNAC continues to be a reliable diagnostic technique in hands of an experienced cytopathologist. The sensitivity of diagnosis of malignant lesions is high, though the rate of tumor type-specific characterization is lower, due to variable cytomorphology. In difficult cases, histologic examination may be employed for accurate diagnosis.
Keywords: Fine needle aspiration; histologic diagnosis; salivary gland; sensitivity; specificity.