DNA ploidy of ameloblastoma and ameloblastic carcinoma of the jaws. Analysis by image and flow cytometry.

Ameloblastomas, the second most common odontogenic tumor, behave as benign locally aggressive tumors. Ameloblastic carcinomas, on the other hand, show histologic features of malignancy and may metastasize. By image cytometric analysis of Feulgen-stained sections from decalcified, formalin-fixed, paraffin-embedded tumors, we compared nuclear DNA content of 17 primary and five recurrent ameloblastomas and five ameloblastic carcinomas. Of the primary ameloblastomas, 14 (82%) were diploid; three (60%) of the five recurrent ameloblastomas were diploid. No significant difference in ploidy between primary and recurrent ameloblastomas or among plexiform, follicular, and acanthomatous types of ameloblastoma was demonstrated. Of the five ameloblastic carcinomas, four (80%) were aneuploid; ploidy was not significantly correlated with the incidence of metastasis. Flow cytometry was performed on three carcinomas; 100% concordance between image and flow cytometric data was seen. Aneuploidy is significantly more common in ameloblastic carcinomas than in ameloblastoma and is a strong predictor for malignant potential.