Dyschromia

DYSCHROMIA, dyschromia, a group of dermatoses characterized by more or less persistent changes in skin color due to a) thickening (hyperpigmentation) or loss (depigmentation) of the normal skin pigment melanin, or b) deposition in the skin of pigments not normally present there of endogenous origin (hemosiderin) or exogenous origin (tattooing, argyria, impregnations). Changes in color depending on the impregnation of the horny layer with dye and washable do not belong here. Often, areas of depigmentation are surrounded peripherally by zones of hyperpigmentation. Dyschromia can be diffuse, even universal (melanoderma), spotted, sometimes reticulate (reticulata); it arises either secondarily, after or during one or another dermatosis, or primarily, immediately as such. The causes of dyschromia are very numerous: 1) external, physical, such as friction, pressure, scratches, radiant energy, heat, etc.; chemical - flies, mustard plasters, tincture of iodine, especially chrysarobin, etc.; 2) internal - diseases of the central nervous system, organs of blood circulation and especially endocrine organs, from infections, especially chronic ones (syphilis, tbc, malaria, leprosy, etc.), intoxications or neoplasms.