Significance of DNA ploidy measurements in Spitz nevi

In 28 Spitz nevi DNA content was determined by video-imaging cytometry. The nevi were selected for this study because of difficulties in differentiation from melanoma and heterogeneity of this type of nevus. Morphological features of Spitz nevi and differences helpful for differentiation between Spitz nevi and malignant melanoma were identified. DNA ploidy was measured in paraffin embedded and fresh tissue material from each patient and the results were comparable. The sample preparation process and video-imaging method are presented in this study. Twenty two (78.6%) lesions contained diploid cell populations, 5 (17.9%) aneuploid and 1 (3.6%) tetraploid cell population. A significant correlation was observed between DNA ploidy measured in fresh tissue and retrospective material. The results indicate the presence of abnormal DNA content in some of the lesions. This observation does not indicate that DNA ploidy cytometry is useful for the differentiation of Spitz nevi from malignant melanoma.