For 4 months, a 73-year-old farmer has had a pruritic rash on one forearm. Because of his exposure to poison ivy on his farm, he was thought to have rhus dermatitis. A potent topical corticosteroid cream was prescribed, but the rash has not improved after 3 weeks of treatment.
What is the most likely cause of this patient’s rash?
A. Contact dermatitis to his watch.
B. Dermatophyte infection.
C. Cutaneous lupus.
D. Polymorphous light eruption.
E. Actinic keratoses.