Huynh N, Sarma D, Huerter C
Omaha
ERYTHEMA AB IGNE
F 53
- Discolored skin over right thigh extending down to the calf for
“many months.”
- No exposure to heating ducts or fire place exposure at home or
work.
- Long term use of electric blanket with direct contact on the
affected skin.
Reticular, erythematous, and hyperpigmented patches on the right distal
extremity.
Skin biosy shows epidermal atrophy and upper dermal perivascular
chronic inflammation
Higher magnification shows dyskeratotic keratinocyte in the epidermis,
mild papillary melanosis and superficial perivascular chronic
inflammation
Elastic stain shows increased elastic tissue especially in the mid-dermis
 Erythema ab igne (EAI) is a rare condition characterized by reticular,
erythematous, and hyperpigmented patches which may result from
chronic exposure to external heat sources.
 Before the advent of central heating EAI was once considered a common
condition most often found on the distal extremities of individuals who
stood or sat close to burning stoves or open fires.
 Cases of EAI have been identified with repeated application of hot-water
bottles or heating pads, in the treatment of chronic pain, such as
backache.
 Certain occupations that chronically expose workers to external heat
sources such as silversmiths, jewelers, bakers, foundry workers, and
kitchen workers have also given rise to cases of EAI.
 EAI has also been reported in individuals using electric space heaters, car
heaters,heated recliners,heating/cooling blankets, heated popcorn
kernels, hot bricks, infrared lamps, wood stoves, coal stoves, electric
stove/heater, peat fires, steam radiators, and most recently laptop
computers as users place computers on their propped legs.
 The pathogenesis of EAI is not yet understood.
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It is suggested that chronic heat exposure denatures DNA in
squamous cells in conjunction with ultraviolet radiation.
 A single episode of heat exposure is insufficient to induce burn or
skin manifestation associated with EAI.
 Chronic heat exposure is needed to accumulate the damages;
generating first a pattern of erythema which then progresses to a
reticular hypo- and hyperpigmentation.
 Although infrequent, subepidermal bullae and diffuse
hyperkeratosis may occur.
 In severe cases, poikiloderma, thermal keratosis, ulceration and
secondary skin malignancy, such as squamous cell carcinoma in
situ, squamous cell carcinoma, and neuroendocrine carcinoma,
(Merkel cell carcinoma), may result although it is quite rare.
 Histologic features of EAI are nonspecific.
 In the early stages, EAI may appear normal on hematoxylin
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and eosin stains.
It may reveal epidermal atrophy, rete effacement, basal
vacuolar changes, and pigmentary incontinence.
The dermis may be infiltrated by lymphocytes,
melanophages, histiocytes, and neutrophils with
postcapillary venules’ dilation and congestion.
Perhaps the most distinguishing feature of EAI is the
increased elastic tissue in the upper and mid dermis and the
presence of squamous cell atypia which resembles actinic
keratoses.
Hyaluronic acid and iron deposition have also been
described.
 EAI is more common in overweight women.
 Patients may be asymptomatic or may present with mild
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sensation of burning or pruritus.
The differential diagnosis includes solar elastosis, erythema
dyschromicum perstans, acanthosis nigricans, actinic
keratoses, livedo reticularis, livedoid vasculitis, poikiloderma
atrophicans vasculare, and cutaneous reactive angiomatoses.
EAI has an excellent prognosis.
Treatment of EAI is immediate removal of heat sources.
5-fluorouracil cream has shown to be effective in eliminating
atypical squamous cells in EAI.
In severe cases where pigmentation persists, tretinoin or
hydroquinone could be used topically.
Biopsy is needed if there are suggestions of malignancy such as
unrelenting ulcer with heaved up borders, or nodules.
REFERENCE:
Huynh N, Sarma D, Huerter C.(2011). Erythema ab igne: a case report
and review of the literature Cutis 88:290-92, PUBMED.