Symmetrical drug-related intertriginous and flexural exanthema/baboon syndrome induced by traditional Chinese medicine.

Background Symmetrical drug-related intertriginous and flexural exanthema (SDRIFE) refers to an uncommon cutaneous adverse reaction that symmetrically involves the buttock and intertriginous areas after systemic exposure to the offending drug and is previously known as baboon syndrome. SDRIFE related with traditional Chinese medicine (TCM) has not been reported. Objective We presented a case of SDRIFE /baboon syndrome induced by TCM, Xi-Huang capsule. Methods A 57-years-old man presented with macular erythematous rash mainly on his intergluteal, inguinal, axillary, popliteal regions for a duration of 5 days. The lesions appeared a day after an oral Chinese patent medicine Xi-Huang capsule for arthralgia. Drug eruption was diagnosed. The rash disappeared completely within a week with immediate discontinuation of Xi-Huang capsule and a short term of systemic therapy with glucocorticosteroids. Patch testing was performed on the patient 1 month after complete resolution. He was patch tested with Xi-Huang capsule (5% and 10% in petroleum) using Finn Chambers on Scanpor tape and T.R.U.E. test system. Five heathy volunteers were also patch tested with the same Xi-Huang capsule. Results Patch testing to 20 common contact allergens including nickel and fragrance were negative. TCM patch test was positive. No positive results were found in five volunteers. Months later, the patient relapsed after an oral herbal Chinese medicine challenge for arthralgia. To avoid the rash recurrence, he stopped taking any Chinese herbal medicine and had complete resolution of disease. Conclusion The Chinese patent drugs for external and oral have unique advantages and have been widely used in many diseases. It is important that dermatologists monitor for clinically significant manifestations of TCM, such as baboon syndrome. Patch testing could help make a definitive diagnosis.