Chronic Discoid Lupus Erythematosus: Impetigo Mimic

Numerous plaques, some with yellow crusting and central scarring, had erupted primarily on the face and neck of a 46-year-old man. A single lesion had developed on his left elbow as well. The lesions were initially diagnosed as impetigo, but they failed to resolve after 2 courses of oral cephalexin. A biopsy of a lesion found superficial and deep perivascular dermatitis with vacuolar and lichenoid interface reaction that is characteristic of lupus erythematosus. The perivascular infiltrate was composed of lymphocytes and plasma cells. A fibrinoid deposit and a follicular plug were present- features that are also characteristic of lupus erythematosus. Dr Robert P. Blereau of Morgan City, La, notes that the patient had no signs or symptoms of systemic disease. The antinuclear antibody (ANA) titer was elevated at 50 IU/mL (normal, less than 7.5 IU/mL); the ANA pattern was speckled. No doublestranded DNA antibodies were detected. C3 and thyroid peroxidase levels were elevated; C4 and thyrotropin levels were normal. The remainder of the lupus panel findings were negative. White blood cell count was 3900/μL; hemoglobin, 15 g/dL; and erythrocyte sedimentation rate, 28 mm/h. Urinalysis and chest film findings were normal. The patient was given oral hydroxychloroquine, 200 mg/d; hydrocortisone cream to be applied to the facial and neck lesions 3 times daily; and high-potency corticosteroid cream for twice-daily use on the elbow lesion. The patient was advised to apply sunscreen to all exposed skin surfaces daily. After 1 week of this regimen, the lesions had cleared significantly; complete resolution was obtained at 2 weeks, with some residual scarring. Although the patient continued his regimen, the facial lesions recurred after 6 weeks. The daily dose of hydroxychloroquine was increased to 400 mg; the lesions resolved within days. Three months later, the dosage of the oral agent was halved, and the lesions recurred. Hydroxychloroquine, 400 mg/d, and applications of a topical hydrocortisone quickly cleared the eruption. Eighteen months after diagnosis, the patient remains on the higher dosage of hydroxychloroquine; occasional mild flares are controlled with hydrocortisone cream. Because of potential retinal and visual acuity damage associated with the long-term use of hydroxychloroquine, this patient had an ophthalmologic evaluation before thera- py began and he continues to have examinations every 6 months. Discoid lupus erythematosus (DLE) is the most common cutaneous expression of systemic lupus erythematosus (SLE); however, systemic lupus does not develop in most patients with DLE, and the result of their ANA test is usually negative. Because this patient had widespread skin lesions and a positive ANA test result, he may be at increased risk for SLE. He is monitored regularly for any signs or symptoms of systemic disease.