The Diagnostic Accuracy of Fine-Needle Aspiration for Parotid Malignancy

Abstract

Objectives:

Determine the sensitivity and specificity of fine-needle aspiration (FNA) in the diagnosis of parotid malignancy and analyze those histologies most often associated with false negative and false positive results.

Methods:

A retrospective chart review was performed for all patients who had a parotidectomy at the University of Wisconsin from 1994 to 2013. Patients who underwent preoperative FNA were identified, and FNA results were categorized as benign, malignant, or indeterminate. Surgical pathology was utilized as the gold standard.

Results:

A total of 771 patients underwent parotidectomy from 1994 to 2013, and 280 patients (36.3%) had a preoperative FNA. Based on surgical pathology, 178 (63.6%) patients had benign disease and 102 (36.4%) had malignant parotid neoplasms. 174 (62.1%) FNAs were benign, 94 (33.6%) were malignant, and 12 (4.3%) were indeterminate. Excluding indeterminate cases, the sensitivity and specificity for FNA in the diagnosis of parotid malignancy were 83.7% (95% confidence interval [CI]: (74.8%, 90.4%)) and 93.0% (95% CI: (88.0%, 96.3%)), respectively. Moreover, FNA correctly categorized malignancy in 83.7% (n = 82) and benign in 92.9% (n = 158) of cases. There were 16 false negatives (16.3%) with mucoepidermoid carcinoma having a diagnostic accuracy of 60% and acinic cell carcinoma 50%. Both were most commonly mistaken for pleomorphic adenoma. There were 12 false positives (7.1%), most commonly pleomorphic adenoma (n = 4) and warthins (n = 3).

Conclusions:

This study demonstrates that FNA has high sensitivity (83.7%) and specificity (93.0%) for the diagnosis of parotid malignancy. However, mucoepidermoid carcinoma and acinic cell carcinoma are more commonly associated with a false negative FNA.