Immunofluorescence of the skin in gold rashes - with particular reference to IgE.

Immunofluorescence studies have been carried out on rashes from 36 patients with rheumatoid arthritis receiving gold therapy. 24 of the rashes were clinically attributed to gold and 12 were diagnosed as coincidental rashes. IgE was found in 6 of the gold rashes and in 4 of the coincidental rashes. Immunofluorescence changes of immune complex vasculitis, lichen planus, or pemphigoid were found in 9 gold rashes while 2 coincidental rashes showed vascular fluorescence for immunoglobulins but nor for complement. Two definite gold rashes showing no changes on immunofluorescence showed perivascular infiltration with lymphocytes on light microscopy. Thus, while immunofluorescence is only marginally helpful in the diagnoses of gold rashes, evidence of an immunological reaction tends to favour a diagnosis of a gold-induced rash.