Two Patients with Solar Urticaria Manifesting Pruritic Erythema

Two patients with solar urticaria are described. They complained of transient pruritic erythema, but not frank wheal, on sun-exposed areas. However, urticarial wheals were elicited by polychromatic radiation in the ultraviolet and visible light ranges; the action spectra for solar urticaria ranged from 400 to 550 nm in case 1 and from UVA to 550 nm in case 2. In patients manifesting only transient pruritic erythema on sun-exposed areas, phototests are essential for making a confident diagnosis of solar urticaria.