A 52-year-old woman with a history of chronic vertebral disk problems and lumbar surgery is referred for evaluation of a discoloration affecting her buttocks and lower back. She denies symptoms related to the dermatitis, but she has had chronic use of a heating pad in an attempt to alleviate underlying back pain. Examination reveals a well-demarcated zone of hyperpigmented confluent macules in a mesh-like pattern. A linear cicatrix is present over the lumbar spine.
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Erythema ab igne (EAI) is an area of localized reticulated erythema and hyperpigmentation. It occurs on areas of the body that are exposed to infrared radiation. Chronic exposure causes injury to the epidermis and superficial vascular plexus. Initially erythematous, over time exposed areas become mottled, manifesting additional shades of brown, blue, or purple.1 Linked in the past to sitting in front of open fires, the condition was known as “fire stains.”2 Although the most common cause today is heating pads, other inciting agents are car seat heaters and laptops.3 Infrared radiation in conjunction with moderate heat is believed to denature DNA within the epidermis and dermis.4
Most cases of EAI are asymptomatic. Avoidance of further exposure to heat is mandatory to prevent worsening. Once discontinued, gradually normalization of pigment is anticipated, although malignant transformation to squamous cell carcinoma has been documented.5
Rebecca Geiger, PA-C, is a physician assistant on staff at the DermDox Dermatology Center in Hazleton, Pennsylvania. Stephen Schleicher, MD, is an associate professor of medicine at the Commonwealth Medical College in Scranton, Pennsylvania, and an adjunct assistant professor of dermatology at the Perelman School of Medicine at the University of Pennsylvania in Philadelphia.
- Dvoretzky I, Silverman NR. Reticular erythema of the lower back. Erythema ab igne. Arch Dermatol. 1991;127:405-6, 408-9.
- Patel DP. The evolving nomenclature of erythema ab igne-redness from fire. JAMA Dermatol. 2017;153:685.
- Salvio AG, Nunes AJ, Angarita DP. Laptop computer induced erythema ab igne: a new presentation of an old disease. An Bras Dermatol. 2016;91(5 Suppl 1):79-80.
- Roth D, London M. Acridine probe study into synergistic DNA-denaturing action of heat and ultraviolet light in squamous cells. J Invest Dermatol. 1977;69:368-372.
- Arrington JH 3rd, Lockman DS. Thermal keratoses and squamous cell carcinoma in situ associated with erythema ab igne. Arch Dermatol. 1979;115(10):1226-1228.