Evaluation of malignant grade of salivary gland tumors: studies by cytofluorometric nuclear DNA analysis, histochemistry for nucleolar organizer regions and immunohistochemistry for p53.

Investigations were carried out in 109 surgically resected salivary gland tumors, 46 adenomas and 63 carcinomas for nuclear DNA content by cytofluorometry, nucleolar organizer regions (AgNOR) by histochemistry and nuclear p53 accumulation by immunohistochemistry. The mean nuclear DNA content and the incidence of aneuploidy as well as the mean number of the AgNOR in carcinomas were significantly higher than those in adenomas. In the DNA histogram pattern, the aneuploidy frequently appeared in high grade carcinoma groups (adenocarcinoma, salivary duct carcinoma, carcinoma in pleomorphic adenoma and oncocytic carcinoma). Immunohistochemical nuclear p53 accumulation was observed in 15 tumors, of which ten showed DNA aneuploidy. In high grade carcinomas, DNA aneuploidy was closely related to p53 immunoreactivity. This study revealed that combined cytofluorometric nuclear DNA analysis, histochemical AgNOR count and immunoreactivity for p53 might be quite useful for evaluating the malignant grade of salivary gland tumors.