Idiopathic guttate hypomelanosis.

Idiopathic guttate hypomelanosis is a common and frequently ignored dermatosis. It appears late in life and increases with aging. The studies so far reported do not support the hypothesis of a residual leukoderma following trauma, and the relation of IGH to chronic solar exposure has not yet been documented. However, the role of ultraviolet A and ultraviolet B in the pathogenesis of this dermatosis should be explored by more refined methods. Although it may be genetically modulated, a multifactorial etiology rather than a single cause is likely. An active depigmenting mechanism may underlie the melanocyte disturbance instead of a simple residual defect. Intralesional triamcinolone in very low concentrations with or without minigrafts of normally pigmented skin could be of some therapeutic value.