CASE
A 41-year-old female presented with a 6-month history of asymptomatic lesions on her lips, face, and arms. The lesions were round, purplish-brown, targetoid macules that ranged in size from 1 to 3 cm (Figure 1). Their pigmentation was variable. The surface of several of the lesions was faintly edematous. No tenderness, increased warmth, or induration was appreciated on palpation. Visits to six different providers had produced four different diagnostic explanations. The patient was treated with oral antibiotics, topical corticosteroids, and topical and oral acyclovir, all of which had no effect.
Type 2 diabetes mellitus had been recently diagnosed, and the patient had started taking metformin prior to the onset of the rash. She appeared to be in good health otherwise. She admitted to taking the metformin only about one-third of the time. The patient said she occasionally took OTC aspirin plus caffeine tablets for pain but denied the use of any other prescription medications. She denied a history of cold sores or of rashes elsewhere.
Further questioning revealed that the lesions, which had begun on the lip, had increased in number and intensity over time but had eventually been limited to the 10 or so seen in this examination. The lesions faded for a few days; then they flared up again and grew darker in color over the course of several weeks. They appeared to be limited to the same areas.
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