Laser Doppler perfusion imaging for the documentation of flare-up in contact allergy to gold

A healed or healing allergic contact dermatitis is easily reactivated to a flare-up if the patient is provoked systemically with his particular allergen. 5 patients with contact allergy to gold were patch tested with a serial dilution of gold sodium thiosulfate. 1 to 2 months later, when positive test reactions were healed, the patients were given 1 intramuscular injection of gold sodium thiomalate. This resulted in a flare-up of patch tests as well as a transient fever and toxicoderma-like reactions. The flaring tests were registered by digital photographs and laser Doppler imaging (LDI). An increased cutaneous blood flow in the formerly positive patch tests was discernible within 1 h after provocation, increased to a vigorous maximum after 4-6 h, and subsided during the following few days. The earliest increase and the highest peak of blood flow were observed in the test areas of the strongest original test concentration. LDI provides a most suitable technique for studying the dynamics of this rapidly developing inflammation of a mainly dermal character.