A month ago, a 33-year-old woman noticed skin changes on her arms and face. The affected areas have recently begun to itch and burn—particularly, the patient notes, since she spent an extended period in the sun over the weekend. She has used an antifungal cream (nystatin) on the rash, to no avail.
The patient denies joint pain, fever, and malaise. She has a sister with multiple sclerosis, but her family history is otherwise unremarkable. The patient’s only medication is oral contraceptives, which she has taken since the birth of her first and only child last year.
EXAMINATION
The patient is afebrile and in no particular distress. A florid red rash covers both cheeks, sparing the nose entirely. The margins are somewhat indurated and redder than the clearing centers. The follicular orifices are somewhat patulous, and a fine scale covers the affected areas of the face. The lateral brachial and triceps (sun-exposed) areas of both arms are similarly affected.
Punch biopsy reveals classic signs of lupus: vacuolar alteration of the basal cell layer, perivascular infiltrate around appendicial structures, and modest epidermal atrophy. Bloodwork yields no evidence of systemic lupus erythematosus (SLE).
What is the diagnosis?