Diagnostic pitfalls of aspiration cytology of salivary duct carcinoma.

BACKGROUND: Salivary duct carcinoma (SDC) is a highly aggressive primary salivary gland neoplasm that resembles intraductal and infiltrating breast carcinoma histologically. The purpose of this study was to review the cytologic features of histologically proven salivary duct carcinomas and to identify the potential pitfalls in cytologic diagnosis.
METHODS: Fine-needle aspiration cytology of nine histologically proven salivary duct carcinomas was reviewed.
RESULTS: The patients' age ranged from 62 to 89 years (median, 69 years). There were eight males and one female. The cytologic diagnoses of these cases were as follows: pleomorphic adenoma (PA) (three cases), high grade carcinoma, not otherwise specified (three cases), mucoepidermoid carcinoma (MEC) (two cases), and atypical cytology with differential diagnosis including MEC, oncocytoma, and acinic cell carcinoma (one case). The spectrum of cytologic findings included broad flat sheets and three-dimensional clusters. There was mild to severe cellular pleomorphism and nuclear atypia. Papillary clusters and cribriforming occasionally were identified. Bland cytologic features and prominent hyaline stroma, shown to represent the dense fibrosis on histologic sections, were identified in three cases cytologically interpreted as PA.
CONCLUSIONS: Fine-needle aspiration of SDC may be difficult to interpret accurately, and bland cytomorphologic features in some cases may lead to a false-negative interpretation; several clinically important pitfalls are demonstrated in our series.