AbstractA comparative assessment was made of dermatofibroma, dermatofibrosarcoma protuberans, and malignant fibrous histiocytoma. The study was comprised of an immunohistochemical investigation using the Ki‐67 monoclonal antibody and a quantitative analysis of cell nuclear DNA using flow cytometry. It was found that the index of Ki‐67 monoclonal antibody labeling, the histogram pattern, and DNA index correlated with clinical malignancy, suggesting the usefulness of these indices for differential diagnosis and evaluation of progno