By Gary M. White, MD
Erythema ab igne is a reticulated pattern of hyperpigmentation that develops at the site of chronic exposure of the skin to heat. This condition represents thermal damage to the skin in areas where the blood supply is sluggish and unable to adequately able to dissipate the heat. There is an increased risk of squamous cell carcinoma.
A reticulated pattern of erythema and later hyperpigmentation at the site of chronic thermal exposure (e.g. from a heater, heating pad, laptop computer or fire) is characteristic. Rarely, bullous lesions may occur. Typical forms are EAI of the shins in a patient who huddles near a fire, facial EAI in cooks, or low-back EAI in patients with low-back pain who frequently use hot water bottles. A special recliner with a built-in heating element has caused EAI in two patients. EAI should always prompt an inquiry as to the source of the heat, and if it is to relieve pain, what the source of the pain is. Underlying pancreatitis, splenomegaly, or cancer all resulting in pain, have been found in this manner. There is an increased risk of squamous cell carcinoma and, rarely, Merkel cell carcinoma.
Kangri cancer (most commonly SCC) is peculiar to the valley of Kashmir as people of all age groups are accustomed to warm their bodies during harsh winters by the use of Kangri baskets. Kangri is an indigenous fire pot used and tucked in between thighs and abdomen to generate warmth, especially during the cold winter months in Kashmir valley (coldest and northern most part of the country). Erythema ab igne develops first, followed by Bowen's disease (usually after an average of 4–5 years), and finally cancer, most commonly squamous cell carcinoma [Indian Dermatol Online J 2016;7:551-3].
No specific treatment is needed other than to avoid the heat. Any growths should be biopsied to exclude squamous cell carcinoma. Topical 5-FU has been recommended in order to reduce the keratinocytic atypia and reduce the risk of SCC [JAAD 1992;129;109].
Kangri EAB and SCC Indian J Dermatol. 2009 Oct-Dec; 54(4): 342–346
Kangri baskets Bowens disease and SCC Indian Dermatol Online J 2016;7:551-3