DNA ploidy in malignant melanoma, skin cancer and pigmented nevi

The determination of DNA content in human cancers is the subject of increasing interest, particularly in view of its potential clinical applications. There are relatively few studies which describe DNA content of skin neoplasms and pigmented nevi. These studies have shown conflicting results. In the present investigation the authors measured DNA ploidy using flow and video-imaging cytometry in 51 malignant melanomas, 20 skin cancers and 48 pigmented nevi. For DNA measurement paraffin embedded tissues and fresh cell smears were used. Clinical and histological data of malignant melanomas were recorded and correlated with DNA ploidy. DNA histograms were examined for DNA aneuploidy by DNA Index. DNA ploidy in primary lesions of melanomas and their metastases were compared. The aneuploidy rate, found in our observation, was significantly higher in whole malignant melanoma group, in clinical Stage II and III, in tumors with thickness greater then 1.5 mm, tumors with Clark level III, IV and V. Another clinical and histological factors did not show significant correlation with ploidy. Aneuploidy was found in 8 of 20 (45.0%) skin cancers. In the whole population of pigmented nevi aneuploid DNA content was identified in 10 nevi (20.1%). The results of this study suggest that aneuploidy seems to be connected with advanced stage of malignant melanoma but it does not replace other prognostic factors. Both cytometric methods can be used for routine DNA ploidy analysis. Ploidy studies are not useful for predicting metastatic potential of primary melanoma. Results obtained from fresh cell smears and paraffin embedded tissues were identical.