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 allerg en. 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 te st reactions were healed, the patients were given 1 intramuscular injection of gold sodium thiomalate. This resulted in a flare-up of patch tests as w ell 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 dis cernible within 1 h after provocation, increased to a vigorous maximum afte r 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 s trongest original test concentration. LDI provides a most suitable techniqu e for studying the dynamics of this rapidly developing inflammation of a ma inly dermal character.