Diagnostic difficulties in the interpretation of fine needle aspirate samples in salivary lesions: diagnostic pitfalls revisited.

Objective: To present our experience in diagnostic errors and pitfalls on aspiration cytology of salivary region in a high volume of cases.

Study Design: In a retrospective review of cytology files of a head and neck referral center from 1990 to 2005, the false positive and false negative interpretations on fine needle aspiration (FNA) of salivary lesions were retrieved. These records and slides were reviewed to identify cytologic characteristics that contributed to false diagnosis.

Results: Of a total of 1,040 salivary FNA samples, 376 cases had a final histologic diagnosis with interpretations of benign or malignant. The sensitivity and specificity for correct interpretation of benign and malignant were 87% and 96%, respectively. The most common false negative cases were acinic cell carcinoma, epithelial myoepithelial carcinoma, adenoid cystic carcinoma and basal cell adenocarcinoma. Benign cases with false positive diagnosis were Warthin tumor and pleomorphic adenoma. Selected positive and negative discordant cases are also discussed.

Conclusion: Knowledge of cytologic overlaps and pitfalls on salivary gland FNA, as well as clinical and radiologic features, may help clinicians arrive at the appropriate diagnosis and reduce false interpretations. Several clinically important pitfalls with nonsalivary tumors of jaw and skin are demonstrated in our series.