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13-year-old boy with reddish-brown rash on leg
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A 13-year-old boy presented to a pediatric dermatology clinic with a new reddish-brown rash on the left anterior leg. He first noticed the rash after getting a new iPad 3 months ago. He reported that he typically rests the iPad on his left thigh while he uses it, sometimes for several hours at a time. He denied pain or pruritus in the affected area. The rash had not been treated. He is an otherwise healthy teenager without complaints.
On exam, the distal anterior left thigh was noted to have several grouped, reddish-brown macules, without atrophy or scale (see Figure). The remainder of his exam was benign.
Distal anterior left thigh displays several grouped, reddish-brown macules, without atrophy or scale.
Image: Krakowski AC
Answer: (D). Erythema ab igne occurs after prolonged and chronic exposure to a heat source that is below the temperature that causes thermal injury (45°C). At first, the skin becomes erythematous with blanching macules. With repeated exposure, hyperpigmentation can develop in a reticular pattern related to hemosiderin deposits and melanocytic activation.
Emily Osier
Andrew C. Krakowski
Erythema ab igne has been historically reported in cold climates on the legs of people who would huddle close to a stove. While this phenomenon decreased after the general use of central heating, it has more recently been linked to heating pad and laptop use. If the heat exposure is removed, the erythema and hyperpigmentation will typically fade over time. However, the hyperpigmentation can become permanent. There is also a slightly increased risk for squamous cell and Merkel cell carcinoma in the areas affected by erythema ab igne, typically with a 30-year latency.
Our patient was counseled to avoid prolonged direct exposure of his skin to the iPad and quickly reported fading of the rash. This case provides another reason to support the AAP’s stance that screen time should be limited!
References:
- Miller KK, et al. Dermatol Online J. 2011;17:28.
- Riahi RR, et al. Dermatol Online J. 2012;18:5.
- Steadmon MJ, et al. J Pediatr. 2013;doi:10.1016/j.jpeds.2013.07.040.
For more information:
Emily Osier, MD, is a clinical research fellow in pediatric dermatology at Rady Children’s Hospital, San Diego. She can be reached at 8010 Frost St., Suite 602, San Diego, CA 92123; email: ejosier@gmail.com.
Andrew C. Krakowski, MD, is an attending physician at Rady Children’s Hospital, San Diego.
Disclosure: Osier and Krakowski report no relevant financial disclosures.