Case In Point: Erythema Ab Igne

This Case In Point also appeared in the October 2005 issue of Consultant, Vol 45, No 12.

A 14-year-old African American boy presented during the winter months with a painless, nonpruritic, periumbilical rash that had been present for approximately 1 month. Initially bluish, the rash had become dark brown.

The patient denied fevers, chills, night sweats, nausea, vomiting, jaundice, abdominal pain, dysuria, or diarrhea. He had asthma, which was controlled with a fluticasone/salmeterol combination inhaler, montelukast, and (as needed) albuterol. He also had a history of allergic rhinitis (which was treated with loratadine) and attention deficit disorder (which was managed with extended-release methylphenidate). He lived in an inadequately heated home and slept on a heating pad to stay warm.

The patient was a well-nourished young man with normal vital signs, height, and weight. Physical examination revealed a reticulated, hyperpigmented, nonblanching rash that emanated from the umbilicus and covered the entire abdomen and extended toward the thorax. He also had a left varicocele. There were no other physical abnormalities (results of a neurologic evaluation and examination of the HEENT, neck, chest, and heart were normal). The abdomen was nontender without hepatosplenomegaly or masses.

The patient was Tanner stage 2-3. He had reasonably well developed muscles. His back was straight with no scoliosis. There was no lymphadenopathy.

The white blood cell count was 6800/µL; hemoglobin, 12.8 g/dL; and hematocrit, 37.6%; platelet count, 333,000/µL; mean corpuscular volume, 82.8 µm³; red cell distribution width, 13.5%, with 56% polymorphonuclear leukocytes, 24% lymphocytes, 12% monocytes, 7% eosinophils, and 1% basophils. His international normalized ratio was 1.0, and his partial thromboplastin time was 28.2; erythrocyte sedimentation rate, 5 mm/h; total protein, 7.3 g/dL; albumin 4.3 g/dL; aspartate aminotransferase level, 20 U/L; alanine aminotransferase level, 15 U/L. His rapid plasma reagin test was nonreactive.

CT of the abdomen and pelvis revealed no pelvic mass. The kidneys, liver, and spleen were normal, as were chest films.

The patient returned in 6 weeks for a follow-up. He had stopped sleeping with a heating pad several weeks before that visit, at which time the rash had spontaneously resolved.

Discussion continues on page 2.

Discussion continued from page 1.
ABOUT THE RASH

This young man presented with an unusual rash on his abdomen that resolved spontaneously. His medical workup was essentially normal and his history revealed that he had been applying local heat to the area of the rash. When this heat was no longer applied, the rash disappeared.

On initial evaluation, it was unclear whether the rash might represent some underlying abdominal organ disease, such as cirrhosis with portal hypertension, or a tumor with skin discoloration that resulted from the development of collateral vessels. Although the abdominal rash in this patient had a vascular net-like appearance, it did not blanch as would blood vessels, and there was no superficial thrombophlebitis on palpation of the skin.

Also possibly of concern was the presence of a varicocele. Varicoceles can signal venous stasis from an underlying tumor or thrombophlebitis of central veins if found on the right side or if the varicocele persists when the patient is supine. This patient's varicocele occurred on the left side, was palpable only when he was standing, and did not cause pain or testicular atrophy. It was therefore considered benign. Nevertheless, because of the unusual nature and vascular pattern of the rash, a CT scan of the abdomen and pelvis was performed.

The differential diagnosis for this rash includes cutis marmorata, livedo reticularis, and erythema ab igne.

Cutis marmorata is a reticular bluish discoloration of the skin that assumes a marbled appearance without hyperpigmentation. It resolves with warming of the skin. This marbled appearance occurs in 50% of young healthy children and is frequently found in those with trisomy 21 syndrome.

Livedo reticularis is a painless, reddish blue mottling of the skin found usually on the extremities in a reticular or fishnet pattern. It is rarely present on the trunk. The discoloration can become permanent and is frequently associated with tingling/numbness. Rarely, swelling and ulcers complicate this condition. This usually is associated with exposure to cold temperatures or with emotional turmoil. It is believed that the blanched areas of skin are secondary to a vasospasm of the perpendicular arterioles that perforate the skin from the subcutaneous tissue. The bluish periphery around the blanched area is caused by deoxygenated blood in the surrounding horizontally arranged venous plexuses. Livedo reticularis can be caused by other conditions, including Raynaud phenomenon, acrocyanosis, obstructive arterial disease, connective tissue disease, hypertension, vasculitis, or hyperviscosity states. The young man in our case had nothing in his history or laboratory test results that would suggest any of these disorders.

Erythema ab igne is the most likely diagnosis in this case. This syndrome begins with a transient pattern of erythema with subsequent hyperpigmentation, atrophy, and (rarely) subepidermal bullae or hyperkeratotic changes. It is associated with heat exposure from various sources, including fireplaces and stoves. It can also occur on exposure to heating pads applied for pain,¹ car heaters,² hot baths,^1,3 hot popcorn kernels applied for arthritis relief,⁴ and even heat from laptop computers.^5,6 Although the condition has been previously associated anecdotally with underlying medical conditions such as pancreatitis, malignancy,⁷ or chronic back pain, the application of heat has been more recently implicated as the cause. The presence of erythema ab igne in inpatients who use heating pads can complicate the diagnosis.¹

Aside from the skin discoloration, erythema ab igne is usually asymptomatic. The diagnosis can be confirmed with a punch biopsy, which shows epidermal atrophy and flattening of the dermo-epidermal junctions, collagen degeneration, and an increase in dermal elastic tissue. Squamous cell carcinoma has been reported on rare occasions in patients with erythema ab igne. Therefore, it is prudent to monitor patients periodically for changes in the appearance of the rash.

Treatment consists of discontinuing the heat applications. In severe cases in which the rash does not resolve, laser treatment may be beneficial.

References:

REFERENCES:

1. Dellavalle RP, Gillum P. Erythema ab igne following heating/cooling blanket use in the intensive care unit.

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2. Helm TN, Spigel GT, Helm KF. Erythema ab igne caused by a car heater.

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3. Lin SJ, Hsu CJ, Chiu HC. Erythema ab igne caused by frequent hot bathing.

Acta Derm Venereol.

2002;82:478-479.
4. Donohue KG, Nahm WK, Badiavas E, et al. Hot pop brown spot: erythema ab igne induced by heated popcorn.

J Dermatol.

2002;29:172-173.
5. Jagtman BA. Erythema ab igne due to a laptop computer.

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7. MacHale J, Chambers F, OConnell PR. Erythema ab igne: an unusual manifestation of cancer-related pain.

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2000;87:107-108.