DNA flow cytometry and glial fibrillary acidic protein reactivity in pleomorphic adenomas of the salivary glands

OBJECTIVE: To evaluate and correlate morphologic features, glial fibrillary acidic protein (GFAP) reactivity and DNA content parameters in 32 pleomorphic adenomas of the salivary glands. STUDY DESIGN: The adenomas were subclassified according to the proportion of stroma and type of stromal differentiation. DNA flow cytometry was carried out on paraffin-embedded material. GFAP reactivity was determined immunohistochemically and evaluated as the percentage of positive cells. Follow-up ranged from 17 to 71 months; no recurrences were observed. RESULTS: Seven cases were aneuploid, 10 peridiploid and 15 diploid. Nondiploid tumors had a significantly higher S-phase fraction. Nondiploid adenomas were significantly associated with a greater percentage of stroma, while S-phase fraction showed only a trend toward being higher in tumors with a greater quota of stroma. Ploidy type and S-phase fraction were unrelated to sex, age, tumor diameter or site. GFAP reactivity was unrelated to subtype or S-phase fraction; a higher frequency of diploid tumors was seen among cases with a greater number of reactive cells. CONCLUSIONS: Aneuploidy is present in a significant percentage of typical cases. It is unrelated to tumor bulk and appears to have no effect on recurrence as long as surgical excision is complete.