A 35-year-old woman consulted a dermatologist because of a persistent facial rash. Physical examination demonstrates an erythematous rash, without blistering or ulceration, involving both cheeks and the nose. The nasolabial folds are relatively spared. The dermatologist also notes scattered erythematous, firm, maculopapular lesions elsewhere on the woman's face and on exposed areas of the neck, upper chest, and elbows. Careful examination of the scalp demonstrates a few areas of focal alopecia. On questioning, the woman repos that she has had the rash more or less continuously for about six months, and that it gets much worse when she is exposed to sunlight. Which of the following autoimmune diseases would MOST likely produce this patient's skin problems?

Systemic lupus erythematosus (SLE) is a systemic autoimmune disorder in which tissues and cells are damaged by pathogenic autoantibodies (especially antinuclear antibodies) and immune complexes. Approximately 90% of systemic lupus erythematosus occurs in women. SLE is associated with a wide variety of manifestations, including characteristic skin rashes, ahritis, anemia, seizures, psychiatric illness, and may affect the kidneys, lungs, and hea. The rash involving the nose and cheeks is the characteristic malar "butterfly" rash of SLE; significant features include the rash distribution, fixed erythema, sparing of the nasolabial folds, and exacerbation with sunlight exposure. The rash is not the only cutaneous manifestation of lupus; alopecia and the maculopapular rash described in the case may also be seen. The rash of dermatomyositis is characteristically described as a lilac or heliotrope discoloration of the upper eyelids accompanied by periorbital edema. Progressive systemic sclerosis, or scleroderma, produces thick, dense skin secondary to dermal fibrosis. Rheumatoid ahritis characteristically produces subcutaneous rheumatoid nodules. Ref: Costner M.I., Sontheimer R.D. (2012). Chapter 155. Lupus Erythematosus. In L.A. Goldsmith, S.I. Katz, B.A. Gilchrest, A.S. Paller, D.J. Leffell, N.A. Dallas (Eds), Fitzpatrick's Dermatology in General Medicine, 8e.