Histopathological And Ultrastructural Study On Melasma

Objective:To study the histopathological features of facial melasma skin in comparsion with adjacent normal skin Through histopathological and ultrastructural study.Then understanding the histological lesions in patients with chloasma morphological characteristics and pigment distribution from the histological level.Discuss the possible reasons of Chloasma,and research on the pathogenesis of Chloasma.Methods:Biopsies were taken from both melasma lesional skin and adjacent perilesional normal skin in 11 cases with melasma.The sections were stained using haematoxylin and eosin, Fontana-Masson and immunostaining for melanocytes.The ultrastructure of the skin was also examined.Then use computer image analysis technique for quantitative analysis of skin lesions observed in patients with chloasma research.Results: The amount of melanin was significantly increased in all epidermal layers in melasma skin.Fontana-Masson staining showed that compared with non-lesion area full-thickness skin lesions of Chloasma melanocytes a marked increase in particle size distribution,of which the most obvious increase was in the basal layer pigment,acantholysis of keratinocytes can be seen clearly in the formation of melanin cap.NKI immunohistochemical staining showed that the depth of skin lesions of patients with chloasma increased compared with non-staining.lesion area staining positive melanocyte cell body was obviously larger,the number of melanocytes was not significantly increased.Computer image analysis:compared with non-skin lesions,pigment zone in skin lesions of Chloasma(PA/1E)increased 68.7%,the content of melanocytes(MC/1E) increased 0.2%,the ratio of basal melanocytes and keratinocytes(MC / KC)increased 1.0%.Transmission electron microscopy observation:compared with non-lesion area,more residues can be seen in lesion area of Chloasma within the stratum corneum of the melanosome,acantholysis of keratinocytes have a large number of phagocytic stageâ…£melanosome,base melanocytes underlying mitochondria,Golgi apparatus,rough endoplasmic reticulum and ribosomes are abundant,â…¢,â…£melanosome period increased significantly.Conclusion:The results suggest that the number of melanocyte in skin lesions of patients with chloasma has not increased.the incidence may be related to a variety of factors such as endocrine disorders,ultraviolet radiation,caused by genetic and other local skin melanocyte melanin synthesis.Chloasma is characterized by epidermal hyperpigmentation,possibly caused both by an increased activity of melanogenic enzymes and by an increased function of melanosome transfer.