Augmentation spectrum in solar urticaria.

A 24-year-old woman had solar urticaria that was activated by wavelengths ranging from 320 to 420 nm, mainly ultraviolet A light. The irradiation of visible light before exposure to activating wavelengths significantly enhanced an urticarial reaction in an augmentative but not in an additive fashion. The examinations using a monochromator revealed that the augmentation spectrum ranged from 450 to 500 nm. Postirradiation of the spectrum had no effect. The inhibition spectrum was also determined in longer wavelengths ranging from 550 to 600 nm. Both postirradiation and preirradiation of the inhibition spectrum exerted their effects. The augmentation spectrum revealed no effects on the wheal formation induced by histamine or compound 48/80 in the patient. The existence of augmentation spectrum has never been reported in solar urticaria, although the inhibition spectrum has been described by several authors.