A complex photodermatosis: solar urticaria progressing topolymorphic light eruption

GIRISH K.PATEL, D.J.GOULD, J.L.M.HAWK AND JANE M.MCGREGOR PhotobiologyDepartment, St John’s Institute of Dermatology, St Thomas’ Hospital, London SE1 7EH, UK

Accepted for publication 15 January 1998

Summary

We report an unusual case of localized solar urticariawhich progressed on each occasion to polymorphic lighteruption (PLE); this was initially noted following pro-vocation by narrow band ulraviolet B (311–313 nm)phototherapy.

Case report

A 38-year-old woman presented with an 8-year history of aseasonal, itchy, urticated, followed by a firmer, morepapular eruption across the chest, neck, shoulders andoccasionally the face; it did not affect the hands andtypically began in February or March and settled by theautumn months. It would occur within several minutes ofexposure to natural sunlight and resolve by 2–3 days.Monochromatic irradiation tests (300–600 nm) were initi-ally normal on the standard sites, namely on either side ofthe midline of the upper back. An initial diagnosis ofpolymorphic light eruption (PLE) was made and treatmentwith a narrow band ultraviolet (UV)B (311–313 nm)desensitization regimen initiated. However, several minutesafter an initial whole body dose of 30 mJ/cm2, she devel-oped a widespread urticarial eruption of the upper chest,arms, and two areas of the back different from thoseinitially tested with the monochromator, along with sparingof all other sites.

Investigations revealed a normal full blood count,normal serum urea and electrolyte concentrations andnormal liver function tests. Antinuclear antibody andextractable nuclear antigen titres were also negative, aswas quantitative porphyrin analysis of the blood, urineand faeces.

Following the immediate reaction to narrow-bandUVB phototherapy, further monochromatic irradiationtests were performed at the affected sites. These nowrevealed immediate urticarial reactions at 300 nm on the

anterior chest and upper arms but not other sites,including those where previous monochromatic irradia-tion tests had been performed, nor at other wavelengths.Solar simulated irradiation (1 kW Oriel Solar Simulator)also provoked an immediate urticarial response of theanterior chest and shoulders, but not any other sites(Fig. 1). The urticaria resolved within hours but 12–24 hlater, at previously irradiated urticated but not unaffectedsites, a papular eruption consistent with PLE appeared(Fig. 2). Skin biopsy then confirmed this diagnosis,showing parakeratosis, spongiosis and a perivascularlymphocytic infiltrate.

A final diagnosis of localized solar urticaria evolvingrapidly into PLE was thus established. The patient wastreated with a twice weekly desensitization psoralen photo-chemotherapy (PUVA) regimen covered with the anti-histamine Coratidine 10 mg and prednisolone 25 mg given1 h before the UVA (315–400 nm) exposure. Following16 treatments, she was then untroubled by either the PLEor solar urticaria during the subsequent summer.

Discussion

Idiopathic solar urticaria is a rare disorder first describedby Merklen in 1904.1 It is an urticarial reaction followingexposure of the skin to either natural sunlight or artificialradiation. Although there are no good epidemiologicaldata on its prevalence in the general population, in oneseries of 203 photosensitive patients referred to a special-ist clinic in the USA,2 the condition comprised only 4%of the diagnoses, compared with PLE and chronic actinicdermatitis (CAD), which comprised 26 and 17%, respec-tively. In another series by Khoo et al.3 in a Singaporeskin referral centre, 5.3% of all such conditions weresolar urticaria again compared with PLE and CAD whichcomprised 13 and 5.3%, respectively.

Solar urticaria usually presents between the ages of10 and 50 years, with a greater incidence in women,typically with a sensation of burning or itching of theexposed skin followed usually within minutes by erythemaand wealing. Occasionally, in severe cases, additionalsymptoms may be headache, nausea, bronchospasm and

Clinical and Experimental Dermatology 1998; 23: 77–78.

77q 1998 Blackwell Science Ltd

Correspondence: Dr G.K.Patel, 102 St. Kingsmark Avenue, Chep-stow, Monmouthshire, NP6 55N, UK.

even syncope. Characteristically lesions resolve over 1–2 h, persistence for greater than 24 h suggesting the muchrarer solar urticarial vasculitis.4

Solar urticaria is most often induced by a spectrum ofUV and visible wavelengths, although this spectrum fora given patient may vary with time5 and be enhanced6 ordiminished7 by preceding longer wavelength irradiation.8

Relatively monochromatic solar urticaria, as appar-ently present in our patient, is very rare, having beendescribed only twice before, in one patient at 4909 and

another at 380 nm.5 In both cases, later re-testingrevealed a broadening of the action spectrum, markedlyin one in whom re-testing after 17 years revealed thewavelengths from 300–600 nm induced the condition. Itis also apparently unusual for solar urticaria to localize tospecific sites, although this has been described oncebefore in a series of three patients, where the eruptionwas referred to as fixed solar urticaria;10 all these hadinvolvement of the chest, as in our case.

Our patient in summary appears to have the complexphotodermatosis of solar urticaria rapidly progressing toPLE. Such a clinical picture is highly unusual in ourexperience, although a delayed papular response follow-ing solar urticaria was thought by Magnus et al. to bequite common.11 It is not entirely clear whether thislatter phenomenon is PLE as we now describe since theprevious reports were not supported by histopathology.Nonetheless, the localization of PLE to sites of solarurticaria in rare patients suggests there may very possiblybe a common inducing photoallergen involved in suchcases.

Acknowledgement

The authors would like to thank Jacqui Nagel, photo-biology technician in the Department of Photobiology,for her assistance.

References

1. Merklen P. Urticaire. La Pratique Dermatologique 1904; 728–71.2. Fotiades J, Soter N, Lim H. Results of evaluation of 203 patients

for photosensitivity in a 7.3-year period. J Am Acad Dermatol1995; 33: 597–602.

3. Khoo SW, Tay YK, Tham SN. Photodermatoses in a Singaporeskin referral centre. Clin Exp Dermatol 1996; 21: 263–8.

4. Armstrong R, Horan D, Silvers D. Leucocytoclastic vasculitis inurticaria induced by ultraviolet irradiation. Arch Dermatol 1985;121: 1145–8.

5. Murphy GM, Hawk JLM. Broadening of action spectrum in apatient with solar urticaria. Clin Exp Dermatol 1987; 12: 455–6.

6. Horio T, Fujigaki K. Augmentation spectrum in solar urticaria.J Am Acad Dermatol 1988; 18: 1189–93.

7. Hasei K, Ichihashi M. Solar urticaria: Determination of actionand inhibition spectra. Arch Dermatol 1982; 188: 346–50.

8. Harber LC, Holloway R, Wheatley V et al. Immunologic andbiophysical studies in solar urticaria. J Invest Dermatol 1963; 41:439–43.

9. Ravits M, Armstrong R, Harber LC. Solar urticaria: clinicalfeatures and wavelength dependance. Arch Dermatol 1982; 118:228–31.

10. Reinauer S, Leenutaphong V, Holzle E. Fixed solar urticaria. JAm Acad Dermatol 1993; 29: 161–5.

11. Ive H, Lloyd J, Magnus IA. Action spectra in idiopathic solarurticaria. Br J Dermatol 1965; 77: 229–43.

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Figure 1. Photograph 10 min after solar simulated irradiation (face,neck and upper arms shielded) showing erythema and wealing of solarurticaria. Note sparing of skin protected by high factor sunscreenpreviously applied.

Figure 2. Photograph 24 h after irradiation showing polymorphiclight eruption. Note sparing of skin at protected sites.

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