Fine needle aspiration cytology of basal cell adenoma of the salivary gland: a cytohistological correlation study of 35 cases.

OBJECTIVE: In order to evaluate the possibility of a specific cytological recognition of basal cell adenoma (BCA) we reviewed our experience with 35 histologically proven cases. Few series describing cytological features of BCA are available and diagnostic cytological criteria are not well established.
METHODS: This study was based on 41 cytology samples from 35 patients with BCA. Thirty-five aspiration procedures were performed pre-operatively and six on tumour recurrence. Nineteen of the 35 patients were men and 16 women. The mean age at diagnosis was 55 years old (range 24-92). The series includes one non-representative case. Except for one tumour located in the upper lip, all of them involved the parotid gland.
RESULTS: Aspirates were cellular, showing groups with dense, homogeneous metachromatic stroma and single cells. Relevant features were the trident-like configuration of groups, intimate relationship between neoplastic cells and stroma and cellular polymorphism. In approximately half of the cases a precise diagnosis was given. Most of the remaining tumours were diagnosed as benign but they were difficult to differentiate from pleomorphic adenoma. Regarding malignancy, there were two misdiagnoses of acinic cell carcinoma, due to high epithelial cellularity along with scarcity of stroma, and one case was considered to be suspicious of malignancy.
CONCLUSION: BCA shows characteristic cytological features that allow a precise diagnosis. The main differential diagnosis is epithelial-rich pleomorphic adenoma, while acinic cell carcinoma is a potential false positive.