Salivary gland tumours studied by means of the AgNOR technique.

Difficulty is sometimes encountered in distinguishing between pleomorphic adenoma, adenoid cystic carcinoma and adenocarcinoma, especially in small biopsies from salivary glands. The argyrophil (AgNOR) staining technique for nucleolar organizer regions (NORs) has been applied to a series of benign and malignant salivary gland tumours. We studied 35 salivary gland tumours, 13 benign and 22 malignant. In all specimens clearly defined silver-stained intranuclear AgNOR dots were visible. The differences between the numbers of AgNORs in the benign and malignant groups, notably pleomorphic adenomas, adenoid cystic carcinoma and adenocarcinoma, were highly significant. In view of this difference we propose that the AgNOR staining technique is of diagnostic help in distinguishing between these salivary gland tumours.