Morphometric analysis of melanocytic tumors. A study of nuclear area and density.

Because the differential diagnosis of melanocytic tumors is sometimes difficult, we performed a morphometric analysis of 20 benign nevi, 20 malignant melanomas, and 10 Spitz's nevi. The nuclear pleomorphism and the maturation to the depth of the tumor were quantified by measuring nuclear area and nuclear density at serial levels of the tumor (every 220 microns of thickness). Data obtained were analyzed statistically. Linear regression was used to represent the variation of nuclear area to the depth, and the standard deviation of nuclear areas reflected nuclear pleomorphism. We attempted to separate different tumors from each other using the Jacknife procedure and morphometric data. Using the Jacknife procedure rather than the usual histological procedures, we were able to distinguish benign nevi from Spitz's nevi and malignant melanoma in as many as 92% of cases, but we distinguished Spitz's nevi from malignant melanoma in only up to 60% of cases. In conclusion, we found it difficult to distinguish between Spitz nevi and melanoma using nuclear morphometric parameters. Other studies using new morphometric parameters are needed in order to improve our ability to make this discrimination.