Small, erythematous papules on the face, scalp, and neck

A man, aged 56 years, presents with a 3-month history of a rash on his face, scalp, and neck. The rash is slightly pruritic, and its cosmetic appearance is very bothersome to the patient. The patient reports that the rash was worsened with sun exposure. His primary care physician thought that the patient had acne and had treated the patient ...