Fine needle aspiration biopsy of salivary gland tumours. Problems and pitfalls

A review of all fine needle aspiration biopsies of salivary gland lesions performed at the Flinders Medical Centre during a 9-year period revealed a number of cases in which there was a discrepancy between the initial cytology report and the definitive diagnosis by histology examination. The most common problem was that of atypical features in pleomorphic adenoma, raising a suspicion of a low-grade malignant tumour in 4 cases. One mucoepidermoid carcinoma and one acinic cell carcinoma had been wrongly diagnosed as Warthin's tumours on the basis of the presence of sheets of bland epithelial cells with oncocyte-like cytoplasm. One trabecular monomorphic adenoma was misdiagnosed as adenoid cystic carcinoma, and one adenoid cystic carcinoma as pleomorphic adenoma. The cytologic patterns of these cases are presented and discussed.