Derm Dx: A rash about the mouth and chin

A 21-year-old woman presents for evaluation of a rash about her mouth and chin. The dermatitis has been waxing and waning in intensity for approximately 2 years. It clears when treated with oral prednisone and then flares shortly after discontinuation. Examination reveals erythema and tiny pustules. She is currently applying mometasone cream to the affected areas.