DIFFERENTIATION BETWEEN MALIGNANT MELANOMAS AND BENIGN MELANOCYTIC NEVI BY COMPUTERIZED DNA CYTOMETRY OF IMPRINT SPECIMENS

Recently image analysis (IA) and DNA-cytophotometry (CP) have proved t o be useful for the differentiation between benign and malignant melan ocytic lesions on paraffin sections. Since on sections, these procedur es are very time-consuming, we tested in the present study whether IA of imprint specimens, which can be evaluated in less than 30 minutes, might also be sufficient. In 39 malignant melanomas (MM), 18 melanocyt ic nevi (MN), and 6 dysplastic nevi (DN), 12 different morphometric an d DNA cytometric features were determined in 100 randomly selected nuc lei. In univariate analysis, 5 features were found to be significantly different between the benign and malignant groups (p<0.0001): mean va lue (MAREA) and standard deviation (SAREA) of nuclear area and the 80t h, 90th, and 95th percentiles of DNA distribution. Using SAREA, die be st univariate feature, 82.5% of the cases could be correctly separated . In multivariate analysis with a combination of three features - stan dard deviation of nuclear area (SAREA), mean DNA value (MDNA), and 95t h percentile of DNA distribution (PERC95) - a correct diagnosis was ac hieved in 89.5% of the cases. Results obtained in the cases of DN indi cated an increased proliferation, but did not allow the separation of DN from MM and MN. Since our technique allows a rapid analysis without loss of tissue, which might be important for histological analysis, a nd the classification rates are equal or still higher than reported in studies on sections, imprints of melanocytic lesions seem to be most appropriate for the calculation of DNA cytometric features as helpful diagnostic criteria in equivocal melanocytic lesions.