A 25-year-old woman with type 2 diabetes mellitus comes to the emergency department for evaluation of a hyperpigmented lesion on the shin. The lesion appeared as a small reddish-brown macule 3 years ago and has gradually increased in size. During the past several months, the lesion has become indented and increasingly tender. Cutaneous examination reveals a 3-cm sclerotic reddish brown patch with central yellow deposits (Figure 1). Laboratory evaluation includes a random blood glucose level of 217 mg/dL (12 mmol/L). The patient denies systemic symptoms, including fevers and chills, and is primarily concerned about the changing appearance of the lesion and the new-onset tenderness.
Lee SY, Shen L, Keimig EL. A Solitary Red Patch. JAMA. 2014;311(22):2328-2329. doi:10.1001/jama.2014.132