Erythema ab igne.

Erythema ab igne is a reticulated, erythematous, hyperpigmented dermatosis resulting from chronic mild to moderate heat exposure. The authors present two cases of erythema ab igne, one from a hot water bottle to treat chronic low back pain and another from a heated automobile seat. They review other reported etiologies and highlight scenarios in which military medical providers may encounter erythema ab igne.