The Role of Fine-Needle Aspiration in Parotid Pleomorphic Adenoma

Objective: Fine-needle aspiration (FNA) biopsy is often used as a well-accepted and both sensitive and specific diagnostic adjunct in the workup of parotid masses. In the case of pleomorphic adenoma, the most common benign tumor of the parotid gland, we examine cytopathologic reports to assess the performance of FNA for this particular histologic diagnosis. Method: A total of 317 patients who underwent parotidectomy over the past 5 years and met eligibility criteria of 1) primary parotid tumor, 2) age greater than 18 years, and 3) availability of pathology (FNA, intraoperative frozen section, final pathology) were reviewed. Clinical history and demographics, physical exam findings, and intraoperative findings were noted. Results: Pleomorphic adenoma was noted on final pathology in 136 patients (42.9%). Interestingly 24 (17.6%) of these patients had initially undergone FNA and been given a incorrect diagnosis, despite the FNA being “diagnostic.” One patient received false positive diagnosis of malignancy by FNA. Of the 24 patients with incorrect diagnosis on FNA, 15 (62.5%) received the correct diagnosis of pleomorphic adenoma with intraoperative frozen section, though one patient received a false positive for malignancy and underwent surgical upstage unnecessarily. For pleomorphic adenoma, it appears that diagnostic sensitivity increases from 82% for FNA to 92% with frozen section. Conclusion: While FNA is commonly used as preoperative diagnostic adjunct for parotid masses, one must exercise caution, even in the context of a diagnostic sample, as nearly 18% of pleomorphic adenomas were not identified. Fortunately, misdiagnosis was benign 95% of time, and subsequently had no surgical implications.