Parotid gland fine-needle aspiration cytology: an approach to differential diagnosis.

Parotid glands can undergo a wide range of pathologic changes that may be difficult to characterize by clinical features alone. No single diagnostic modality is currently accepted unequivocally as the definitive approach to parotid gland enlargement or tumors. Although it is generally accepted that fine-needle aspiration (FNA) biopsy is useful in the preoperative setting, the accuracy is highly dependent on both operator experience and the interpretative skills of the cytopathologist. Results of FNA biopsy must be considered in a global context, in conjunction with clinical and radiographic findings. The objectives of this paper are threefold: (1) to define the clinical role of parotid FNA, such that pathologists performing and/or interpreting such specimens have a clearer understanding of the expectations of our surgical colleagues; (2) to clearly describe a protocol for the performance of parotid FNA biopsy, including a discussion of complications and pitfalls; and (3) to present the cytologic differential diagnoses of diverse clinicopathologic parotid gland processes that may present as generalized enlargement, cystic lesions, or discrete masses.