Quality Assuarance on Fine Needle Aspiration Cytology of Malignant Salivary Gland Neoplasms

To evaluate the quality of fine needle aspiration cytology diagnosis on malignant salivary gland neoplasms, cytologic findings were correlated with histologic diagnosis of 56 surgically removed malignant salivary gland tumors. Seven cases (12.5%) were insufficient, 23 cases (41.1%) were diagnosed as malignant, 17 (30.4%) cases were accurately diagnosed by histologic subtype, and 9 cases (16%) were diagnosed as benign. Five out of 9 false negative cases were misdiagnosed as pleomorphic adenomas. Except the cases with insufficient specimen, overall sensitivity was 81.6%, and the sensitivity varied according to the histologic subtype; 91% in salivary duct carcinoma, 100% in carcinoma ex pleomorphic adenoma, 50% in mucoepidermoid carcinoma, 63% in adenoid cystic carcinoma, and 50% in acinic cell carcinoma. The diagnostic accuracy differed among cytopathologists irrespective of periods after acquisition of board of pathologists. These results confirm that salivary gland neoplasm can be easily misdiagnosed in fine needle aspiration cytology and a great caution should be given in diagnosing the benign appearing salivary aspirates to avoid under-diagnosis of malignant neoplasm with low grade cytologic atypia.