Treatment of idiopathic guttate hypomelanosis with liquid nitrogen: light and electron microscopic studies.

Idiopathic guttate hypomelanosis is a common skin disorder of unknown cause. Our studies have shown that significantly fewer dopa-positive melanocytes are in the white macules of idiopathic guttate hypomelanosis than in normal skin. By electron microscopy we observed that the melanocytes in the lesional skin were round and less dendritic with fewer melanosomes than in normal pigment cells. Lesions gently frozen with liquid nitrogen repigmented in 6 to 8 weeks. The number of dopa-positive melanocytes was significantly greater in the repigmented areas than in untreated lesions but less than in normal skin.