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Bullous erythema ab igne

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Bullous erythema ab igne
Aysin Kokturk MD,1 Tamer Irfan Kaya MD,1 Kiymet Baz MD,1 Ayca Cordan Yazici MD,1 Duygu Dusmez Apa MD,2 and Guliz Ikizoglu MD1
Dermatology Online Journal 9(3): 18

From the Departments of Dermatology(1) and Pathology(2), Faculty of Medicine, Mersin University, Turkey.


Erythema ab igne is a localized, cutaneous condition, consisting of reticulate hyperpigmentation, dusky erythema, epidermal atrophy, and telangiectasia, all the result of repeated exposures to heat. We describe a patient with a bullous form of erythema ab igne: bullae and crusts within a localized area of reticular, brown, macular pigmentation on the lateral side of the left leg, an area that had repeated close exposure to an electrical heater over the previous 3 months. We believe that bullous erythema ab igne, something rarely reported in the literature, should be considered a well-defined variant of erythema ab igne; it may be more common than the literature suggests.

Erythema ab igne (EAI) is a reticulate hypermelanosis with erythema resulting from repeated mild heat exposures that induces injury to the epidermis and superficial vascular plexus. The initial manifestation of EAI is the presence of red macules at the site of exposure. These macules are most often found on the back or on the lower legs of women. With continued episodes of heat exposure, the skin reaction evolves into a hyperpigmented reticulated macular eruption with dusky erythema, telangiectasia, and epidermal atrophy. Symptoms of burning or itching may be described by patients.[1, 2] Although bullae are rarely seen, we present a case of bullous EAI.

Case report—A 57-year-old man presented with bullous and crusted lesions localized to the lateral aspect of his left leg. He had several tense bullae with crusting, present at the inferior margin of a localized area of reticulate, brown, macular pigmentation. The history revealed repeated, close exposures to an electrical heater for the previous 3 months. He complained of a burning sensation at the site of the bullae. He was otherwise healthy. Blood count, routine urinalysis, liver and renal function tests, serum glucose and electrolyte levels, and erythrocyte sedimentation rate were all within normal limits.

Histopathology examination of a bullous lesion showed subepidermal separation of the epidermis, and increased elastic fibers and dilated capillaries in the dermal papillae, characteristic findings of EAI (Fig. 1). The epidermis was thin, and there were no rete pegs. Hydropic degeneration of basal cells, melanophages in the upper dermis, and a mild, superficial, perivascular-lymphocytic infiltrate were also present. Elastic tissue stain (Elastic Van Gieson) revealed fragmented and disrupted elastic fibers. There were no immune deposits on direct immunofluorescence of perilesional skin. Although a clinical diagnosis of erythema ab igne with thermal burns was considered, we would have expected more epidermal necrosis, particularly at the site of separation of the epidermis. Considering the history with the clinical and histopathological findings, the diagnosis of bullous EAI was thought to be most likely.

After he stopped using the electrical heater, the bullous lesions evolved into hemorrhagic crusted lesions that disappeared in 20 days, leaving postinflammatory hyperpigmentation (Fig. 2). This evolution also supported our belief that the lesions were heat-induced.

Figure 1Figure 2
Histopathology showing subepidermal separation (hematoxylin-eosin; original magnification X100) (Fig. 1). Hemorrhagic crusted lesions of erythema ab igne (Fig. 2)

In 1986, Horio and Imamura reported a case of EAI associated with blister formation.[3] In biopsy specimens, they observed orthokeratotic hyperkeratosis, acanthosis with saw-tooth, elongated rete ridges, Max Joseph spaces, Civatte bodies, and a bandlike cellular infiltration in the upper dermis. They observed cytoid-body-like deposits of IgM in the papillary dermis. In addition, they observed characteristic findings of EAI, such as an increased number of elastic fibers and dilatation of capillaries in the dermal papillae. Because of clinical and histopathological features similar to those of lichen planus, they considered the presentation to be bullous lichen planus developing on erythema ab igne. Horio and Imomura proposed that bullae formation resulted from lichen planus. They claimed that the case described by Little, who did not record the histopathological findings, was similar and had similar clinical findings.[4] In 1996, Flanagan reported three cases with the title bullous erythema ab igne.[5] The cases presented with bullae at the base of EAI. Skin biopsies of all three cases showed subepidermal separation of the epidermis. Direct immunofluorescence was negative in two of the cases, and the third one had nonspecific, weak, patchy deposition of IgM along the dermo-epidermal junction.

Our patient does not show features typical of lichen planus, but has similar histology and immunofluorescence to the bullous EAI cases reported by Flanagan. We consider our case to be the bullous variant of EAI. Arriving at the diagnosis of bullous EAI may be easy if supported by the history. However, if the history is vague or if the patient denies heat injury, confirming that diagnosis can be difficult. A combination of history, physical findings, and histology should confirm the diagnosis.

We describe a case of bullous EAI, something rarely reported in the literature. We propose that bullous EAI be considered a defined variant, and that it may be more common than suggested by the literature.


1. Kennedy CTC, Mechanical and Thermal Injury, Rook A, Wilkinson DS, Ebling FJG, eds, Textbook of Dermatology, 6th ed. Oxford: Blackwell Scientific Publications, 937-938, 1998.

2. Shahrad P, Marks R, The wages of warmth: changes in erythema ab igne, Br J Dermatol. 97: 170-186,1977.

3. Horio T, Imamura S. Bullous lichen planus developed on erythema ab igne. J Dermatol. 13: 203-207, 1986.

4. Little EG. Erythema ab igne, or alternatively lichen planus. Br J Dermatol Syphilol. 41: 277-278, 1929.

5. Flanagan N, Watson R, Sweeney E, Barnes L. Bullous erythema ab igne, Br J Dermatol. 134: 1151-1165, 1996.

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