Objective: To describe the histologic changes associated with preoperative fine-needle aspiration biopsies of benign parotid lesions and the features that distinguish these changes from malignant neoplasms.
Materials and methods: Ten benign parotid lesions with a recent history of preoperative fine-needle aspiration were selected, including pleomorphic adenoma (4 cases), oncocytic adenoma (3 cases), myoepithelioma (1 case), Warthin tumor (1 case), and lymphoepithelial cyst (1 case).
Results: A spectrum of histologic alterations were observed. Alterations included squamous cell metaplasia (8 cases), infarction and necrosis (4 cases), subepithelial stromal hyalinization (3 cases), acute and chronic hemorrhage and inflammation with multinucleated giant cells (all cases), granulation tissue with subsequent fibrosis (all cases), cholesterol cleft formation (1 case), pseudoxanthomatous reaction (1 case), pseudocapsular invasion (1 case), and microcystic degeneration (2 cases). In cases with exuberant squamous metaplasia, necrosis, or subepithelial stromal hyalinization, a diagnosis of squamous cell carcinoma or low-grade mucoepidermoid carcinoma was seriously considered.
Conclusions: Knowledge of a previous fine-needle aspiration procedure and awareness of its effects on histology of the subsequent parotidectomy specimens are necessary to avoid potential misdiagnosis.