Solar Urticaria Inhibited by Visible Light

Abstract

A 25-year-old man with solar urticaria is described. The action spectrum ranged from 400 to 500 nm. An inhibition spectrum was found to be in the visible light range above 660 nm. Simultaneous or alternate exposure to ‘blue-violet light’ and ‘red light’ mostly inhibited weal formation. The urticarial reaction was not blocked by local injection of antihistamines and not prevented by histamine depletion with polymyxin B sulfate. These data suggest that histamine may not play a major role in weal production in this case.

Solar urticaria

“…56,57 Theorized mechanisms behind inhibition spectra include: (1) mast cell stabilization, (2) direct inactivation of photoallergen, (3) competitive inhibition, or (4) binding blockade. In the first theory, Torinuki et al 51 proposed that inhibition spectra resulted in mast cell stabilization; this theory was largely disproven by Horio et al, 52 who showed that histamine responsiveness remained unchanged after inhibition spectra irradiation. The second theory was proposed by Horio et al 52 and suggested instead that the inhibition spectrum caused inactivation of the photoallergen.…”

Narrowband ultraviolet B phototherapy is a suitable treatment option for solar urticaria

“…Experimental and clinical findings suggest direct destruction of photoallergen or its conversion back into precursors. [11][12][13] Competitive occupation by altered photoallergen of IgE binding sites on skin mast cells, as well as down-regulation of IgE production and blockage of IgE-mediated release of histamine from mast cells implicated in the therapeutic effect. 14 UVA photoprophylaxis does not alter tissue histamine content or mast cell numbers.…”

“…14 UVA photoprophylaxis does not alter tissue histamine content or mast cell numbers. [11][12][13] PUVA therapy is another successful prophylactic modality. Possible mechanisms of action similar to those described for UVA therapy have been suggested and PUVA is claimed to induce a more lasting and effective tolerance than UVA phototherapy alone although the hazard of psoralen skin toxicity, including carcinogenesis, must be taken into account.…”

Solar Urticaria: A Case with Good Therapeutic Response to Cimetidine

“…Occasional therapeutic successes for so lar urticaria have been achieved with the re gimens including H, or conventional antihistamines, such as chlorpheniramine [11], homochlorcyclizine hydrochloride [2,12], hydroxyzine hydrochloride [4], methylbenzyltetrahydrocarboline [5], and antimalarial agents [6]. In general, however, the drug therapy for solar urticaria is not satis factory.…”