An unusual case of solar urticaria is reported. The clinical reaction consisted of multiple wheals with pseudopodia formation occurring in the light-exposed sites. This picture differed from the classical pattern of a single large wheal occupying the entire exposed site with no pseudopodia formation.
Action spectrum studies indicated that the response was due to wavelengths longer than 4,000 Angstroms (A) with the most effective rays lying between 4,000 A and 5,000 A.
Studies for other physical allergies (heat, cold, and cholinergic urticaria), uroporphyria, and protoporphyria were negative.
Occlusion of the arterial blood supply prevented the abnormal reaction from occurring.
Passive transfer of the response to a normal recipient with the patient's serum failed.
The effect of synthetic antimalarial therapy, as studied by the threshold sensitivity technique, revealed at least a 32-fold increase in resistance after six weeks of treatment.
EPSTEIN JH, VANDENBERG JJ, WRIGHT WL. Solar Urticaria. Arch Dermatol. 1963;88(2):135–141. doi:10.1001/archderm.1963.01590200023004
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