Discrimination between benign and malignant melanocytic skin lesions by multivariate analysis, quantitative S-100 immunohistochemistry, nuclear morphometry and DNA cytometry

OBJECTIVE: To determine whether combined quantitative immunohistochemistry of S-100, nuclear morphometry and DNA image cytometry improves discriminati on between benign and malignant melanocytic skin lesions (MSLs). STUDY DESIGN: S-100 protein expression was measured in tissue sections of M SLs using an image cytometry system. Localized areas of high S-100 expressi on were used to identify regions in sequential,facing sections in which mor phometric and cytometric features of nuclei, including DNA ploidy, were als o measured. RESULTS: Malignant cases had significantly higher S-100 protein staining in tensity, larger nuclei and greater DNA content (P<.05). High staining inten sify for S-100 protein weakly correlated with variation in size of the mean nuclear area (P=.04) and DNA content (P=.03). Combining the features of nu clear area and DNA integrated optical density in areas of high-intensify st aining for S-100 protein discriminated move accurately between 12 benign an d 16 malignant areas than any of the features alone (P=.0003). CONCLUSION: Combined multivariate quantitative immunohistochemical, morphom etric and DNA cytometric analysis greatly improves discrimination between b enign MSLs and malignant melanoma. Larger test sets are required to confirm the promising results of this initial study.