Erythema ab igne caused by a car heater.

Erythema ab igne is a reticulated erythematous hyperpigmented eruption that occurs after chronic exposure to heat. In the past, the shins were the most common area of involvement, but with the widespread availability of central climate control in most buildings the incidence has decreased dramatically. New causes of erythema ab igne have been noted that have been caused by such heat sources as therapeutic chairs with built-in heaters. We present a case in which prolonged and close contact of the legs to a car heater led to erythema ab igne. Practitioners must be aware of the changing causes of erythema ab igne so that an appropriate history can be obtained.