What Caused This Increased Pigmentation?

Increased pigmentation on her lower back is noted by a 38-year-old woman who has used a heating pad for several months for low back pain.

What condition are you looking at here?

A. Erythema annulare centrifugum
B. Erythema chronicum migrans
C. Erythema dyschromicum perstans
D. Erythema ab igne
E. Erythema gyratum repens

(Answer and discussion on next page.)

Answer: Erythema ab igne

Erythema ab igne, D, arises from chronic exposure to infrared radiation. It presents with a reticulated, hyperpigmented, and telangiectatic dermatosis.

Erythema chronicum migrans is seen in patients with Lyme disease. Erythema dyschromicum perstans is patchy pigmentation found most often on the backs of Hispanic women. Frequently associated with an underlying malignancy, erythema gyratum repens is a gyrate erythematous scaling condition. Erythema annulare centrifugum, a disease of unknown cause, is an annular gyrate erythema with trailing scale.