A woman in her 20s presented with almost equally sized, round erythematous plaques with central pallor and confluent blisters at the periphery on both forearms. Older lesions showed central crusts. According to the patient, the lesions recurrently appeared during the last 9 years, with a symptom-free period of 2 years (Figure, A). She could not identify or recall a specific cause for these skin lesions and denied self-inflicting them. She had been treated with antibiotics (cefuroxime) as well as with topical steroids (dexamethasone) but denied any lasting effect. Her family history was without abnormalities. She reported being vaccinated against varicella zoster virus and was not immunocompromised.