Cytologic features of the cell-stroma interface are useful in distinguishing between monomorphic adenomas of the basal cell type and adenoid cystic carcinoma. In basal cell adenomas, the collagenous stroma interdigitates with adjacent cells, whereas in adenoid cystic carcinoma, the two are separated by a sharp smooth border. Furthermore, the stroma of basal cell adenomas can contain rare spindle cells or capillaries, but the cylinders of adenoid cystic carcinoma are acellular. The authors review their experience with five cases of basal cell adenoma, and three cases that were designated "minimally pleomorphic adenomas." The latter group showed the small blue cell pattern of basal cell adenoma at the time of fine-needle aspiration, and histology revealed only small foci of typical pleomorphic adenoma. With the exception of one cystic case, the cell-stroma interface of basal cell adenoma was observed in all eightThe recognized clinical utility of salivary gland fine-needle aspiration (FNA) stems from the fact that most common mass lesions are readily diagnosed by these means. Typical examples of pleomorphic adenoma, Warthin's tumor, and various types of sialoadenitis are frequently encountered and usually straightforward for the cytopathologist. "4 However, uncommon presentations of common tumors, unusual neoplasms, and some metastatic deposits can present diagnostic difficulties.The term monomorphic adenoma was previously applied to a wide range of salivary gland lesions, many of which are now cataloged under more specific designations, including oncocytomas, Warthin's tumors, neoplasms with sebaceous differentiation, and basal cell adenomas. 8 The latter usually occur in the parotid where they are encapsulated and often partially cystic. Basal cell adenoma is distinguished from pleomorphic adenoma by the absence of the chondroid and myxoid foci that typify pleomorphic adenoma and facilitate its recognition in FNA samples. Some otherwise typical examples of basal cell adenomas will harbor microscopic foci of pleomorphic adenoma, and will be designated as cellular pleomorphic adenoma in surgical pathology. When only small chondromyxoid foci are present, they may be missed by the aspirating needle, leading to a smear pattern of basal cell adenomas, despite ultimate classification of the excised tumor as pleomorphic adenoma. We suggest designating such cases as "minimally pleomorphic adenomas."Basal cell adenomas are subclassified on the basis of architectural patterns in histologic material. Thus, the tubular, trabecular, solid, and canalicular types feature small uniform cells growing in various configurations.

We reviewed the clinical and fine-needle aspiration (FNA) findings in 20 patients with poorly differentiated carcinomas presenting initially as parotid or as submandibular masses. There were 11 primary tumors and nine metastatic malignancies in 14 males and six females ranging in age from 39 to 89 yr (median = 66). The tumor types included three primary carcinomas with oncocytic features, three additional cases of high-grade parotid carcinoma, one case of primary neuroendocrine carcinoma, two examples of malignant mixed tumor, one high-grade mucoepidermoid carcinoma, and a single example of malignant lymphoepithelial lesion. Six patients with metastatic carcinoma had previous diagnoses of malignancy. In the three remaining individuals, primary carcinomas of the lung (two cases), and an unknown primary site presented initially as parotid masses. Five examples of metastatic squamous cell carcinoma, one metastatic basal cell carcinoma, and two metastatic renal cell carcinomas were identified. One parotid lymphoepithelioma was interpreted cytologically as an atypical lymphoproliferative process suggestive of Hodgkin's disease. Nineteen cases (95%) were correctly classified as carcinoma at the time of FNA. High-grade carcinomas aspirated from the parotid may be primary, but are frequently metastatic to either the gland, or to an intraparotid lymph node. Our experience indicates that some metastatic carcinomas present at this site, without a previous history of malignancy. Distinguishing primary from metastatic lesions has important therapeutic implications.