A 50-year-old woman with a history of meralgia paresthetica, Graves disease, and diabetes mellitus presented to our medical center with symptomatic hypoglycemia. On physical examination, a nonpruritic, macular, nonblanching, brown hyperpigmentation in a reticular pattern on the left anterior thigh (pictured) was noted. The patient reported chronic heating pad use over the affected area for several weeks for management of chronic pain. A dermatologist was consulted, and erythema ab igne (EAI) resulting from excessive heating pad usage was diagnosed. After the patient discontinued heating pad use, the rash improved but did not resolve. Repeated exposure to infrared radiation from heat or at levels insufficient to induce thermal burns can result in EAI.¹ Mild cases of EAI regress after removal of the heat source, but topical retinoids and hydroquinone may be used to reduce hyperpigmentation.² Although rare, squamous cell carcinoma and neuroendocrine carcinoma (ie, Merkel cell carcinoma) can arise from EAI.³