THE DEVELOPMENT AND COURSE OF TEST REACTIONS TO GOLD SODIUM THIOSULFATE

In our department, gold sodium thiosulfate has become the 2nd most com mon allergen in routinely patch tested dermatitis patients, with a rat e around 10%. Test reactions to this compound often appear late, somet imes so late that active sensitization may be suspected. This study wa s performed to study the time course of the allergic reaction to gold sodium thiosulfate and to elucidate whether late test reactions mean a ctive sensitization. 10 patients with contact allergy to gold sodium t hiosulfate (0.5% pet.) were retested epicutaneously (e.c.) and intracu taneously (i.c.) with dilution series. The clinical course was followe d for 2 months with initially short intervals, later more extended. Du ring the entire study, 26 positive e.c. reactions were diagnosed. With in the Ist week, 17 (65%) were recorded. 12 reactions (46% of 26) were noted at the ordinary reading, 3 days after test application. After 1 0 days, another 9 reactions (35%) appeared. The patients with the latt er reactions also had positive test reactions within the Ist week. Aft er 2 months, 9 reactions remained. Out of 30 i.c. tests applied, 25 be came positive within 1 week. 19 (76%) of these reactions changed in mo rphology from thin infiltrates to deep nodules. Another 4 nodules appe ared in patients with previous negative i.c. tests. All 23 nodules rem ained after 2 months. E.c. and i.c. test reactions to gold sodium thio sulfate are long-lasting. Positive patch test reactions emerging after 10 days do not automatically imply active sensitization. To diagnose contact allergy to gold sodium thiosulfate, the ordinary reading at da y 3 is insufficient; even reading at 1 week is insufficient and must b e supplemented by a reading at 3 weeks. Al the i.c. test reactions, ho wever, appeared within 1 week and, in several, a dermal nodule was for med.