Glial fibrillary acid protein immunoreactivity in fine-needle aspiration of salivary gland lesions: a useful adjunct for the differential diagnosis of salivary gland neoplasms.

The value of immunocytochemical staining for glial fibrillary acid protein (GFAP) in salivary gland lesions was investigated in 33 fine-needle aspiration smears. The study utilized cytologic material from ten pleomorphic adenomas, six normal salivary glands, three cases of chronic sialadenitis, three Warthin's tumors, two adenoid cystic carcinomas, three adenocarcinomas, two malignant mixed tumors, one acinic cell carcinoma, and three mucoepidermoid carcinomas. All tested pleomorphic adenomas stained positively. The adenoid cystic carcinomas and the cases of chronic sialadenitis, along with the low-grade mucoepidermoid carcinoma, were negative for GFAP immunoreactivity. These results indicate that immunostaining for GFAP may be a valuable aid in the diagnosis of pleomorphic adenoma; GFAP may be especially helpful in distinguishing those cases for which the differential diagnosis includes the aforementioned salivary gland neoplasms.