Evaluation of cystic salivary gland lesions by fine needle aspiration: an analysis of 21 cases.

Objective: To analyze the potential sources of diagnostic errors and overall accuracy rate of the fine needle aspiration biopsy (FNAB) diagnosis of cystic salivary gland neoplasms.

Study Design: A 10-year (1993-2002) retrospective review of the cytopathology slides from the Division of Cytopathology, Department of Pathology, Long Island Jewish Medical Center, New Hyde Park, New York, identified a total of 97 consecutive salivary gland FNAB cases that microscopically were interpreted as representing cystic lesions. Of these, 21 cases had histologic follow-up at our institution.

Results: A correct diagnosis was rendered by FNAB in 15 of 21 (72%) cases. This included 9 Warthin's tumors, 2 mucoepidermoid carcinomas, 2 simple cysts, 1 cystadenoma and 1 abscess. Clinically insignificant discrepancies were identified in 3 of 21 (14%) FNABs. Clinically significant misdiagnoses were identified in a further 3 of 21 (14%) cases.

Conclusion: A systematic approach to the diagnosis of cystic salivary gland lesions by FNAB can result in a correct diagnosis in > 70% of cases. Careful attention should be directed at identifying the extracellular fluid components present (mucoid vs. watery proteinaceous) as well as the predominant cellular component (e.g., lymphocytes, histiocytes, epithelial cells and oncocytes). It is important to recognize, however, that occasionally epithelial cells may not be detected on FNAB of cystic salivary gland lesions, as a result of either cellular dilution by cystfluid or inadequate sampling. Regardless, with all FNABs tentatively diagnosed as a mucinous cystic lesion, the referring clinician should be informed that a low grade mucoepidermoid carcinoma cannot be ruled out.