Heater-Associated Erythema Ab Igne: Case Report and Review of Thermal-Related Skin Conditions

Erythema Ab Igne with Histological Features of Keratosis Lichenoides Chronica

Erythema ab igne (EAI) is a localized, hyperpigmented and reticulated dermatosis at sites of chronic heat exposure. Within longstanding skin lesions of EAI, hyperkeratotic lesions may emerge and can potentially transform into pre-malignant or malignant skin lesions. A 55-year-old woman presented for the evaluation of multiple hyperkeratotic lesions along with a reticular patterned hyperpigmentation on her right knee, an area that had repeated and prolonged exposure to a heat source over a period of several months. Based on her clinical history and the physical examination of her lesions, she was diagnosed as having a hyperkeratotic form of EAI. A skin biopsy was performed to rule out malignant alteration, but the histopathological findings were supportive of keratosis lichenoides chronica.

Erythema Ab Igne: A Rare Presentation of Toasted Skin Syndrome With the Use of a Space Heater

Erythema ab igne, also known as toasted skin syndrome, is an acquired asymmetric hyperpigmented dermatosis that is caused by repeated exposure to moderate heat or infrared radiation. Hyperpigmentation is caused by the degeneration of elastic fibers and basal cells resulting in the release of melanin. Historically found in bakers and industrial workers, this condition has recently resurfaced in medical literature with the use of novel heat sources such as laptops and heated car seats. While this condition can resolve spontaneously after removal of heat exposure, delay in diagnosis and persistent exposure can lead to permanent pigmentation or progression to Merkel cell carcinoma, basal cell carcinoma, and squamous cell carcinoma.

Erythema Ab Igne in a 12-Year-Old Boy Diagnosed via Telemedicine

In March of 2020, an otherwise healthy 12-year-old boy developed a unilateral patch of reticulated erythema limited to his left lower extremity. The child could not be examined in the clinic due to limited in-person appointments during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, so he was examined via a telemedicine visit. The diagnosis of erythema ab igne was made as his mother verified that the child was spending approximately two hours per day playing video games in the cold basement of his house, with a space heater positioned close to his left leg. Our case of erythema ab igne is unique due to the relatively young age of the affected child, and it provides an example of how this diagnosis can be made via a telemedicine visit. Being able to recognize the classic appearance of erythema ab igne through the scrutiny of photographs and obtaining pertinent history can preclude the need for an in-person visit during times when home sequestration may be a necessity.