Actinic prurigo. The possible etiologic role of an amino acid in the diet.

Actinic prurigo is a chronic skin disease commonly associated with cheilitis and conjunctivitis. This peculiar disorder, with ethnic, genetic, environmental, clinical and histological features, represents an abnormal reaction to sunlight. It occurs in American Indians of Canada, United States and most frequently in Latin America where it involves not only indigents but also the mixed ancestry (Mestizo) population. In analogy to what is well known about pellagra, a disease also with solar influence and a deficient intake of tryptophan or niacin in diet, it is our hypothesis that actinic prurigo patients develop their disease due to, among other factors, a diet poor in proteins.