Erythema Ab Igne Workup

Updated: Oct 04, 2016
  • Author: Laila I Al-Otaibi, MBBCh, MSc; Chief Editor: Dirk M Elston, MD  more...
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Workup

Laboratory Studies

Laboratory findings may be abnormal if the erythema ab igne is associated with a systemic disease.

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Procedures

Perform a 3- or 4-mm punch biopsy if the diagnosis of erythema ab igne is uncertain.

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Histologic Findings

Microscopic changes in erythema ab igne depend on the type of heat, the length of exposure, and the area of the body involved. [30]

Epidermis

Histologically, erythema ab igne is similar to actinic keratoses, with the epidermis showing squamous atypia. [30] Early erythema ab igne shows atrophy of the malpighian layer and increased epidermal and upper dermal melanin with dermal vasodilatation. [15] Advanced cases show epidermal vacuolation, focal hyperkeratosis, and dyskeratosis. [15] Epidermal dysplasia within abnormal elastic tissue may also be seen. [15] In early erythema ab igne lesions, epidermal atrophy with loss of the rete ridges is seen. Some patients show focal or confluent hyperkeratosis, dyskeratosis, keratinocyte atypia, and, occasionally, melanocyte atypia. [37] Hyperpigmentation, with focal degenerative changes of basal keratinocytes, is seen. [37] Similar alterations can be observed in chronic actinic skin damage. [37]

Dermis

Melanin incontinence occurs with melanophages present in the upper dermis. [37] Collagen degeneration and a relative increase in dermal elastic tissue are seen. In contrast to solar elastosis, this is not basophilic on hematoxylin and eosin–stained specimens. [37] Telangiectasis within the papillary dermis and occasional hemosiderin may be seen more commonly on the legs in patients with erythema ab igne. [37] An apparent functional activation of melanocytes with numerical increase of dendritic processes is also observed. [37] Abundant melanophages and occasional elastic fiber alterations as seen, similar to actinic elastosis. No alterations consistent with preneoplastic skin conditions are observed. [37]

Increased elastosis with fragmented collagen fibers are seen. [15] Minimal basophilia and homogenization of elastic fibers, which are prominent in solar elastosis, are seen in erythema ab igne. [15] Both melanophages and hemosiderin are seen in the dermis. [15] Varying degrees of dermal lymphohistiocytic infiltration are present. [15] Extravasation of red blood cells in inconsistent. [15] Accumulation of dermal elastic tissue can be seen, which is an early sign of both UV radiation- and heat-induced skin damage. [30]

Other considerations

Squamous cell carcinoma and Merkel cell carcinoma may arise in the lesions of erythema ab igne on rare occasions. [30] The most common thermally induced cancer, squamous cell carcinoma, tends to occur after a long latent period of more than 30 years. [30] Squamous cell carcinoma in burn scars often begins as a chronic ulcer, which slowly enlarges and tends not to heal. Although these carcinomas tend to be of low-to-intermediate grade histologically, they may also be aggressive, with metastases and a poor prognosis reported in greater than 30% of cases. [30] Merkel cell carcinoma is an aggressive neoplasm, characterized by local recurrence in approximately 30% of cases and up to 30% mortality. [30]

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