PROLIFERATIVE ACTIVITY AND ANEUPLOIDY IN PLEOMORPHIC ADENOMAS OF THE SALIVARY-GLANDS

We used flow cytometry in a retrospective study of pleomorphic adenoma and carcinoma arising in pleomorphic adenoma, using paraffin-embedded tissue, to assess the relationship among proliferative activity, ploi dy, and recurrence or malignant transformation. Twenty-four specimens obtained from 22 tumors were acceptable for analysis (coefficient of v ariation, less than or equal to 7.0), including multiple samples from two tumors. Fourteen tumors (13 benign and one malignant) were diploid . Six tumors were aneuploid: four benign pleomorphic adenomas and two carcinomas arising in pleomorphic adenoma. Two tetraploid tumors were malignant recurrences from the same patient. Of the recurrent tumors ( nine benign and four malignant), 54% were aneuploid. The highest S-pha se fractions were observed in recurrent and malignant pleomorphic aden omas. Immunostaining with p105, a nuclear proliferation antigen, revea led increased proliferative activity in a majority of pleomorphic aden omas. Increased proliferative activity and aneuploidy occurred in beni gn pleomorphic adenomas.