Solar urticaria

Solar urticaria is a rare disorder in which patients develop urticarial lesions after exposure to light from the sun or other sources. The etiology is unknown: some cases appear to be mediated by IgE, but other mechanisms may ultimately be found to be more significant. This disease typically persists for years, but may resolve spontaneously. Although fatalities have not yet been reported, episodes of solar urticaria have produced near-fatal accidents. At best, treatment is difficult, but some techniques have afforded some patients substantial or total relief, even if only temporarily.     

Solar urticaria

A case of solar urticaria is described showing: (1) Action spectra for late erythema (MED), late swelling and wealing with one peak of sensitivity for erythema and wealing at 405 nm. (2) No signs of porphyria. (3) Possibly increased skin mast ceils. (4) Short-lived post-irradiation fibrin deposition. (5) Haemolysis. (6) Apparent suppression of urticaria with the antihistamine Incidal.     

Solar urticaria enhanced through clothing

Solar urticaria is characterized by itching, erythema and wheeling immediately after exposure to radiation in the ultraviolet (UVB, UVA) and visible spectra. Although its exact mechanism remains unknown, evidence supports an immunologic pathogenesis. We describe an unusual patient with solar urticaria who had more severe involvement in skin irradiated with UVA light through white clothing. We propose that optical whiteners in clothing and detergents had absorbed UVA radiation, transforming it into visible light, which was responsible for the urticarial response.     

Solar urticaria in an infant

A 2-year-old girl presented with a history of an erythematous rash which occurred immediately after exposure to sunlight and had been a problem since birth. Extensive laboratory investigations to exclude genophotodermatoses. photosensitivity secondary to metabolic disorders and photoaggravated dermatoses were negative. Monochromator irradiation phototesting demonstrated immediate erythematous flares to all ultraviolet B (UVB). UVA and visible wavelengths up to 500 nm. A diagnosis of solar urticaria was made and she responded to loratidine 10 mg daily. We believe this is the first report of solar urticaria. confirmed by phototesting with a monochromator so early in life.     

Solar urticaria: pre-PUVA UVA desensitization

BACKGROUND: Solar urticaria is an uncommon disorder sometimes difficult to treat. It is characterized by the occurrence of typical whealing reactions on exposed skin a few minutes after sun exposure. The reactions resolve 1 to 5 hours after sun exposure ceases. We report a case evolving over several years, unresponsive to antihistamines and successfully treated by PUVAtherapy performed after UVA desensitization. CASE REPORT: For 3 years, a 22-year-old man developed erythema and itchy wheals at each solar exposure. The lesions appeared on all exposed areas including those usually exposed (face and hand) even in winter. An antihistamine regimen given for several weeks (cetirizine, loratadine) was ineffective. One trial of PUVA therapy led to an urticarial reaction of the entire body. Phototesting showed the minimal whealing dose for UVA was 0.4 J/cm(2). Phototherapy was therefore started by segmentary UVA irradiation at an initial dose of 0.1 J/cm(2). Exposure was then progressively increased allowing initiation of the PUVAtherapy on the 9(th) day with a dose of 0.5 J/cm(2) without whealing reaction. Slow increment PUVA therapy was able to induce good tolerance to sun exposure. DISCUSSION: Solar urticaria may sometimes have a deleterious effect on normal daily life. Severe cases are characterized by a whealing reaction after minimal sun exposure, even on regularly exposed skin. Antihistamines can provide some symptom relief in many patients, but high doses are required. If antihistamines are ineffective, PUVA therapy is indicated. Pre-PUVA UVA desensitization is often necessary. However, exposure to UVA alone has to be repeated every 24 to 48 hours to maintain the refractory state. The advantage of PUVA therapy is a more long lasting protection allowing weekly maintenance sessions.     

Solar urticaria unresponsive to intravenous immunoglobulins

The treatment of solar urticaria (SU) can be difficult. Only a few cases of SU have been treated with intravenous immunoglobulins (IVIg) (as monotherapy or combined with phototherapy), with reported fast and durable increase of solar exposure tolerance. A 61-year-old female with severe UVB- and UVA-induced SU and a 62-year-old female with severe UVA and visible light-induced SU were both treated with a single course of IVIg (total dose of 2 g/kg), infused over 3 days. Phototest, performed 3 months after the treatment, showed only a slight minimal urticating dose improvement, and both patients reported just a moderate and 'transient' subjective improvement. Our patient's poorer response, compared with previous reports, may be due to differences in IVIg's treatment schedules, which are reviewed.     

Solar urticaria successfully treated with intravenous immunoglobulin

Idiopathic solar urticaria (SU) is a rare, debilitating photodermatosis, which may be difficult to treat. First‐line treatment with antihistamines is effective in mild cases, but remission after phototherapeutic induction of tolerance is often short‐lived. Other treatment options include plasma exchange, photopheresis and ciclosporin. We present two cases of severe, idiopathic SU, which were resistant to conventional treatment. Both patients achieved remission after administration of intravenous immunoglobulin (IVIg) and have remained in remission at 13 months and 4 years, respectively. There are only two case reports of successful treatment of solar urticaria with IVIg. In our experience IVIg given at a total dose of 2 g/kg over several 5‐day courses about a month apart is an effective treatment option for severe idiopathic SU. It is also generally safe, even if certainly subject to significant theoretical risks, such as induction of viral infection or anaphylaxis.