It is characterized by the presence of ill-defined, scaly, faintly erythematous patches that subside to leave areas of hypopigmentation. Duration of PA varies from 1 month to 10 years, but most cases resolve over several months to 1 year. Diagnosis is made clinically and treatment consists of skin care and education of the parents about the benign nature of the disorder. Hydrocortisone may decrease erythema, scale, and pruritus, if present. PA is a nonspecific finding that is commonly associated with atopic dermatitis.
Etiology is unknown.
In a study of 9 patients with extensive PA, there was reduction in the density of functional melanocytes in the affected areas without any change in cytoplasmic activity. The melanosomes tended to be fewer and smaller, but their distribution pattern in the keratinocytes was normal. Melanosomal transfer to keratinocytes was generally not disturbed. Histology was nonspecific. Hyperkeratosis and parakeratosis were not consistently present, and it seems unlikely that they played a significant role in the pathogenesis of the hypomelanosis.