FLOW CYTOMETRIC ANALYSIS OF DNA CONTENT AND KI-67-POSITIVE FRACTIONS IN THE DIAGNOSIS OF SALIVARY-GLAND TUMORS

To explore the utility of now cytometry (FCM) for the diagnosis of his topathology of salivary gland tumors, fresh materials taken at surgery from 23 Warthin's tumors, 57 pleomorphic adenomas, and 14 malignant t umors were analyzed for DNA ploidy and proliferative cell activities, including S-phase fraction (SPF), G2- plus M-phase fraction (G2M), and Ki-67-positive fraction. To facilitate this study, glands were taken from all major salivary sites and minor glands in the head and neck. D NA aneuploidy was not detected in the benign tumors. Nine of 14 malign ant tumors showed DNA aneuploidy. The percentage of SPF or G2M of the malignant tumors was significantly higher than those of the benign tum ors. The percentage of Ki-67-positive fraction of pleomorphic adenomas was comparable to that of malignant tumors and was significantly high er than that of Warthin's tumors. Ki-67 of 20% as a cut-off had a sens itivity of 88%, specificity of 100%, and accuracy of 91% for different iating pleomorphic adenomas from Warthin's tumors. In analyzing DNA co ntent and proliferative activities by FCM, we could distinguish among the three major histopathologies of salivary gland tumors. Warthin's t umors showed low SPF+G2M with low Ki-67, pleomorphic adenomas had low SPF+G2M with high Ki-67, and malignant tumor showed high SPF+G2M with high Ki-67. The high percentage of the Ki-67-positive fraction seen in pleomorphic adenomas may reflect their potential biological aggressiv eness manifested as tumor recurrence or malignant transformation.