Diagnosis: Erythema Ab Igne
(The term roughly translates from Latin to mean "redness from fire/heat")
Erythema Ab Igne is a condition of hyperpigmentation that occurs in the skin after both acute and chronic heat exposure. It may be tender or pruritic, but is most often asymptomatic. It is treated with avoidance of the offending heat source. In this particular case, the patient was using an electric heating pad at night to relieve her low back pain. Electric heating pads and hot water bottles are common causes of Erythema Ab Igne. I have also seen it on the shins of persons who sit close to campfires and on the palms of cooks who work close to hot ovens and heat or flames. I did see a case last year on the shins of an office worker who used a space heater under her desk during the winter for extra office warmth. Once the offending heat source is removed, the discoloration will most often fade with time and good emollients, although in a small percentage of patients the area of discoloration persists.
Charles E. Crutchfield III, MD
Clinical Adjunct Associate Professor of Dermatology
University of Minnesota Medical School
Medical Director, Crutchfield Dermatology