The pathology of head and neck tumors: salivary glands, part 4.

Adenoid cystic carcinomas and adenocarcinomas of salivary tissues are more plentiful in minor than in major salivary glands. In the latter, they comprise no more than 10% of tumors. In both sites, however, their clinical course is characterized by local aggressiveness, recurrences, and a relatively torpid and protracted course, eventually leading to death. The clinicopathologic aspects of these two lesions form the major part of this report. Their behavior is contrasted with that of the two other lesions presented: heterotopic salivary tissue, which is seldom the site of neoplasia; and necrotizing sialometaplasia, a self-limited disorder that simulates malignancy both clinically and histopathologically.