Solar urticaria. A report of 25 cases and difficulties in phototesting.
BACKGROUND
Solar urticaria is a rare photosensitive disease, and its differential diagnosis with respect to polymorphous light eruption is sometimes difficult. We report our experience with 25 cases of solar urticaria and discuss the pitfalls in phototesting such patients.


METHODS
The most important locations in this patient series are the V of the neck and the arms, which are similar to those of polymorphous light eruption. In all of the patients, however, the lesions appeared within 30 minutes of sun exposure or phototesting and disappeared within 24 hours. Notably, 12 (48%) of the patients had a history of atopy. Phototesting helps confirm the diagnosis, but, in some patients, this was difficult.


CONCLUSIONS
A negative phototest result from a single light source does not necessarily exclude a diagnosis of solar urticaria. In patients in whom phototesting elicits negative reactions, other light sources should be used, and, if the phototest result is still negative, a provocative test with natural sunlight should be done. Histamine1-receptor antihistamines are a useful first-line therapy, although more severely affected persons may require prophylactic courses of phototherapy or photochemotherapy. The main problem is maintenance treatment.
Ryckaert
S
S
Photodermatology Unit, University Hospital, Leuven, Belgium.
Roelandts
R
R
D000293:Adolescent; D000328:Adult; D000368:Aged; D001132:Arm / Q000473:pathology; D003876:Dermatitis, Atopic / Q000150:complications; D003937:Diagnosis, Differential; D005148:Facial Dermatoses / Q000175:diagnosis / Q000209:etiology; D005533:Foot Dermatoses / Q000175:diagnosis / Q000209:etiology; D006229:Hand Dermatoses / Q000175:diagnosis / Q000209:etiology; D006634:Histamine H1 Antagonists / Q000627:therapeutic use; D006801:Humans; D007868:Leg Dermatoses / Q000175:diagnosis / Q000209:etiology; D008027:Light; D008875:Middle Aged; D009333:Neck / Q000473:pathology; D010778:Photochemotherapy; D010787:Photosensitivity Disorders / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology* / Q000517:prevention & control; D010789:Phototherapy; D012782:Shoulder / Q000473:pathology; D012882:Skin Tests / Q000295:instrumentation / Q000379:methods*; D013472:Sunlight / Q000009:adverse effects*; D013997:Time Factors; D014581:Urticaria / Q000175:diagnosis / Q000188:drug therapy / Q000209:etiology* / Q000517:prevention & control
D006634:Histamine H1 Antagonists