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Hyperpigmented, reticulated rash in a 15-year-old female
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A 15-year-old female presents to your office with rash. She is afebrile and feels well. The patient reported that she noticed the rash 2 weeks before her appointment, and the color has gradually progressed from red to brown. She has not experienced a rash like this before. The patient does not take any medications other than ibuprofen, as needed, and is otherwise healthy. She plays basketball and rides horses.
Due to the cold winter, the patient noted that she has a space heater at her desk while she does homework at night. Her family history is notable for pertinent negatives, but there is no family history of connective tissue disease or clotting disorders.
Physical examination shows reticular, hyperpigmented patches at the bilateral medial legs (Figures 1 and 2). There is neither ulceration nor crusting, and the patches are not tender to palpation.
Figures 1 and 2 show hyperpigmented, reticular patches on the patient’s legs. There is neither ulceration nor crusting, and the patches are not tender to palpation.
Images: Perman MJ
Diagnosis: (B) Erythema ab igne
Case discussion
Erythema ab igne can occur in patients of all ages. Prolonged exposure to a focal source of heat elicits the cutaneous changes over the course of several exposures. Laptops, car-seat heaters, radiators, fires, electric blankets, heating pads, space heaters (as in this case) and other heat sources are all reported triggers. Patients with occupations that expose them repeatedly to heat sources also can be affected as the emitted heat is at a temperature below the threshold for causing thermal burns.
Carrie C. Coughlin
Marissa J. Perman
Patches of erythema ab igne are characterized by erythematous and/or hyperpigmented, reticular patterns. They can be bilateral or unilateral, depending on the position of the heat source. Some patients have bullae associated with the patches. While erythema ab igne itself is benign, there have been reports of squamous cell cancer and Merkel cell cancer rarely arising in lesions on adults after many years.
The differential diagnosis includes livedo reticularis, cutis marmorata, cutis marmorata telangiectatica congenita (CMTC) and chronic graft-versus-host disease. Livedo reticularis is a sign of vasculopathy. Vasculopathy, or noninflammatory occlusion of blood vessels, can be caused by hypercoaguability, such as in patients with antiphospholipid antibodies. It can mimic changes seen with other occlusive thrombi, such as in patients with disseminated intravascular coagulation.
Cutis marmorata is a physiologic change seen as transient “mottling” of the skin. This condition is most common in neonates and infants, and resolves with warming of the skin. Patients with Cornelia de Lange and multiple trisomy syndromes, as well as others, are associated with more persistent cutis marmorata. Cutis marmorata is different than CMTC, which does not improve when infants are warmed. Patients with CMTC exhibit purple-brown reticulated patches that are often associated with atrophy and sometimes with ulceration. When CMTC encompasses much of a limb, that limb can be smaller or larger than the contralateral limb. Patients with GVHD can be distinguished by history.
Initial treatment of erythema ab igne is straightforward: the trigger must be removed. The hyperpigmentation generally fades with time. Some patients have residual hyperpigmentation, which can be treated with topical agents, such as tretinoin. However, treatment should be reserved for cases that prove to be truly persistent. In the few patients with associated skin cancers, these are treated surgically as indicated.
Some patients have used their heating source to treat pain. If there has been a known injury to the site being treated, this is explainable. If there is no known trigger, the source of pain should be investigated, as patients with undiagnosed internal malignancies have been recognized.
Recognition of erythema ab igne and elicitation of a heating source exposure can prevent patients from undergoing extensive, unnecessary workups for vasculopathy. If a patient is using heat to treat pain, the underlying cause of the pain should be addressed.
References:
Huynh N, et al. Cutis. 2011;88:290-292.
MacHale J, et al. Pain. 2000;87:107-108.
Smith ML. Erythema ab igne. In: Bolognia JL, et al, eds. Dermatology. 2nd ed. Vol 2. London, England: Mosby; 2008:1355-1356.
For more information:
Carrie C. Coughlin, MD, is a pediatric dermatology fellow at The Children’s Hospital of Philadelphia. She can be reached at coughlincc@email.chop.edu.
Marissa J. Perman, MD, is an attending physician at The Children’s Hospital of Philadelphia.
Disclosure: Coughlin and Perman report no relevant financial disclosures.