Unilateral toasted skin syndrome

A 36-year-old female came with asymptomatic skin lesions over the left leg of a 1-year duration. On examination, a reticulate non-blanchable hyperpigmented net-like pattern was observed over the left shin [Figure 1]. The right leg was normal and no similar lesions elsewhere in the body. She gave the history of prolonged exposure to heat while cooking in front of an earthen oven with a wood-burning fire on the ground and having tied her saree above the knee to prevent fire particles from damaging the clothes. Thorough history taking and clinical examination revealed a diagnosis of unilateral toasted skin syndrome. The patient was advised to avoid exposure to heat and cover the legs with clothes while cooking.

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Figure 1:

Reticulated hyperpigmented net-like macule over the shin of the left leg shin sparing the right leg.

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Erythema ab igne is derived from the Latin word which means “redness from fire.” It is also called fire stains and toasted skin syndrome. It is caused by chronic long-term exposure to infrared radiation. Although the pathogenesis is poorly understood, studies have shown that heat acts synergistically with ultraviolet (UV) radiation to denature DNA in squamous cells in vitro and chronic UV rays exposure leads to photoimmunosuppression as an adaptive response. Initially, there is transient reticulate erythema which is blanchable; later, it evolves into dusky hyperpigmentation, which is fixed and non-blanchable. Usually asymptomatic but sometimes associated with a burning sensation.^[1] In India, cooking in front of the chulha (low open earthen Indian oven) is common in rural women resulting in long-term exposure to infrared radiation. Prolonged exposure to heat without covering legs with proximity to chulha leads to toasted skin syndrome over the legs. Lifestyle modifications and avoidance of chronic exposure to heat help in the treatment of erythema ab igne and prevent the development of squamous cell carcinoma in long-standing cases.^[2] The primary treatment is avoidance of heat source and topical hydroquinone or retinoids are used for treating the persistent hyperpigmentation.