Fine-needle aspiration cytology of parotid tumours: is it useful?

The efficacy of fine-needle aspiration cytology (FNAC) in the diagnosis of parotid tumours remains a controversial subject. Studies within small departments utilizing experienced pathologists have shown FNAC to have high sensitivity and specificity for parotid tumours. The present study was performed to assess the accuracy and utility of FNAC of parotid tumours within a teaching hospital environment.

One hundred and sixty-nine patients underwent both FNAC and subsequent surgery to the parotid between 1995 and 1999. The results of the FNAC were compared to the histopathological diagnosis obtained from the surgical specimen.

Fine-needle aspiration cytology had an overall accuracy of 56%. Approximately 10% of the FNAC results were non-diagnostic. The sensitivity and specificity for the following diagnoses were, respectively: benign 86% and 61%; malignant 57% and 100%; pleomorphic adenoma 78% and 95%; squamous cell carcinoma 52% and 99%; mucoepidermoid carcinoma 14% and 99% and adenocarcinoma 20% and 100%. Six non-neoplastic conditions were misdiagnosed and all six patients underwent surgery.

Fine-needle aspiration cytology was found to be highly specific for malignancy but its sensitivity for malignancy was poor. The results show that although FNAC is relatively inexpensive and minimally invasive, it cannot be relied upon to provide an accurate tissue diagnosis, may fail to identify malignancy and does not prevent patients undergoing surgery for non-neoplastic conditions.