SOLAR URTICARIA
SOLAR URTICARIA ICD-10: L56.3
• Uncommon sunlight-induced healing confined to exposed body sites.
• Eruption occurs within minutes of exposure and resolves in a few hours. Very disabling and sometimes life threatening.
• Action spectrum is UVB, UVA, and visible light or any combination thereof. Most commonly UVA (Fig. 10-11).
• Solar urticaria is an immediate type I hypersensitivity response to cutaneous and/or circulating photoallergens.
• Therapy: Multiple phototherapy sessions in low but increasing doses on the same day (“rush hardening”); oral immunosuppressive agents or plasmapheresis.
• Prevention: Sun avoidance or sunscreens with high protection factors against action spectrum.
A
B
FIGURE 10-11 • Solar urticaria (A) Since wheals induced by sun exposure are transient and have usually disappeared when a patient comes to the clinic this 62-year-old patient exhibited only residual erythemas on the cheeks and the V of the neck when she was photographed. (B) The patient was subsequently exposed to various doses of UVA and UVB delivered to template test sites on her back and immediately after exposure this picture was taken. UVA test site shows a massive urticarial reaction verifying UVA-induced solar urticaria.