Low-grade and high-grade adenocarcinomas of the salivary duct system.

Adenocarcinomas of salivary glands are encountered less frequently than adenoid cystic or mucoepidermoid carcinomas. They fall into two well-defined clinicopathologic groups: 1) those arising from intercalated ducts and 2) those from the excretory and interlobular ducts. The former, designated terminal duct adenocarcinomas, are low-grade malignancies found preponderantly in the oral cavity, especially the palate. The latter, designated salivary duct carcinomas, are high-grade neoplasms and arise almost exclusively in major salivary glands, especially the parotid gland.