A Computed Image Analyzing System for Quantitation of Melanocyte Morphology in Café-au-Lait Macules of Neurofibromatosis

Abstract

Split-dopa preparation is a commonly used technique to visualize the epidermal melanocytes. It can characterize the number of melanocytes and their tyrosinase (dopa-oxidase) activities. There is not, however, any method to quantitate the morphologic changes of dopa-positive melanocytes in the split preparation. This study designed a computed image analyzing system and evaluated the structure of epidermal melanocytes in café-au-lait macules with comparison to normally pigmented skin in 5 patients with neurofibromatosis. By this method we were able to delineate the melanocyte structure with melanocyte population and coloration of the macules. We found that the population and structure of melanocytes differ greatly depending on the coloration of the café-au-lait macules. The light brown and brown macules showed the normal population of melanocytes with an increase in the area and perimeter of whole cell; the area, perimeter, and diameter of cytoplasm; and the area, length, and breadth of dendrites. In contrast, the dark brown macules revealed a significant increase of the epidermal melanocytes with a decrease in all of these parameters. Thus, the methodologic design presented here may enable a quantitative, two-dimensional analysis of melanocyte structure at the light microscopic level in the normal skin and in various pigmentary disorders.