Application of computerized image analysis in pigmentary skin diseases

Background  Melanocyte number and the amount of melanin pigment are related to diagnosis and treatment of pigmentary skin diseases. Various histologic methods are used, such as Fontana-Masson stain for melanin pigment or immunohistochemical stain for melanocytes. Recently, computerized image analysis has been applied to many fields to avoid interobserver bias. In this study, we applied a computerized image analysis to assess the melanin content and melanocyte density of human epidermis. Methods  We evaluated the skin biopsy specimens (paraffin blocks) from normal human skin (33 ± 6.6, n = 11) and diseased skins; vitiligo (32 ± 10.0, n = 8), melasma (35 ± 8.6, n = 11), and lentigo senilis (40 ± 7.2, n = 11) (mean age ± SD). Each specimen was stained with Fontana–Masson for melanin pigments and immunohistochemical method for melanocytes. Quantitative analysis of melanin pigment and melanocyte number (density) were investigated through two methods: (1) two dermatologists measured the visual scales; and (2) computerized image analysis was used to measure melanin content indices (MCI). The data were evaluated using one-way anova. Results  The visual scale of the Fontana–Masson stain was the highest for lentigo senilis (3.8 ± 0.40), followed by melasma (2.6 ± 0.67), normal skin (1.8 ± 0.60) and vitiligo (0) (P   0.05). Conclusion  We believe this computerized image analysis could be useful tool for diagnosis and comparison of interval changes in pigmentary diseases like melasma or lentigo senilis by quantifying melanin pigments or melanocytes in skin biopsy specimens.