Diagnostic accuracy and utility of fine-needle aspiration cytology in therapeutic management of parotid gland tumours

Introduction and objectives The utility of fine-needle aspiration cytology (FNAC) in parotid tumours remains widely debated. This study aims to evaluate the accuracy of FNAC in diagnosing parotid tumours. Materials and methods We performed a retrospective analysis of patients with tumour disease of the parotid gland treated at a Portuguese Oncology Institute, over a period of 25 years. The preoperative FNAC results were compared with the final histopathological diagnosis. We calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of FNAC for malignancy. Association between malignancy on histopathology and FNAC results were evaluated with the Chi-square test. Results The study sample consisted of 155 patients (77 males and 78 females) with a mean age of 56.6±17.0 years. In 27 cases (17.4%), the FNAC result was indeterminate. In this group of patients there was a higher proportion of malignancy on histology (48.1%) (X2; p<0.001). In the group with a conclusive result on FNAC, the sensitivity and specificity of FNAC for malignancy was 66.7% and 99.0%, respectively. PPV was 94.1% and NPV was 92.8%. Conclusions A benign result on FNAC should be used with caution, due to its low sensitivity for malignancy. An indeterminate result on FNAC should raise suspicion for a malignant tumour.