Erythema annulare centrifugum: an unusual case due to hydroxychloroquine sulfate.

Erythema annulare centrifugum presents as a cutaneous hypersensitivity to diverse causes including fungal and yeast infections, parasitic infestations, drugs, and, rarely, occult malignancies. A prolonged case of erythema annulare centrifugum secondary to the use of hydroxychloroquine sulfate is presented. The prolonged time needed for clearing after discontinuation of the medication is thought to result from the melanocyte-binding characteristics of the drug.