Validity of fine needle aspiration cytology in the diagnosis of salivary gland lesions

Objective: To determine the accuracy of fine needle aspiration cytology (FNAC) in the diagnosis of salivary gland lesions.

Method: A retrospective analysis of 96 FNAC and corresponding histology obtained from salivary gland lesions was done. Sensitivity, specificity, accuracy, positive predictive value, negative predictive value, likely hood ratio and cyto-histological concordance were calculated.

Results: Benign lesions accounted for 79.2 % and 3.1% were malignant. The cyto-histological concordance (C) for benign and malignant lesions was 77% and 18% respectively and nonconcordance (NC) was 22.6% and 9% respectively. The overall rate of deferred diagnosis (DD) was 17.7%, 15.4 % for non-neoplastic lesions, 45.5% for malignant tumours and 12.7% for benign tumours. When the cases of deferred diagnosis were included, the diagnostic accuracy, sensitivity and specificity of the FNAC in identifying malignancy were 97%, 27% and 87% respectively. When cases of deferred diagnosis were excluded the diagnostic accuracy, sensitivity, specificity, positive and negative predictive value and likely hood ratio were 96.2%, 50%, 100%, 100%, 96% and 50% respectively.

Conclusion: The diagnostic accuracy is comparable to several of the other studies. However the diagnostic difficulties due to the presence of low grade malignancy with minimal cellular atypia, existence of various histological types and coexistence of more than one tumour type need to be overcome. To improve the accuracy of diagnosis it is necessary to re-aspirate the solid areas after cyst fluid aspiration, preferably under image guidance.

DOI: http://dx.doi.org/10.4038/jdp.v7i1.5603

Journal of Diagnostic Pathology 2012 (7); 1: 50-58