brand logo

Am Fam Physician. 2006;74(10):1765-1766

Author disclosure: Nothing to disclose.

A 19-year-old woman presented with a rash on her back (see accompanying figure). She denied experiencing pain, itching, joint aches, malaise, or photosensitivity. The patient had no personal or family history of connective tissue disease. Physical examination revealed reticulated erythema on her lower back. There was no evidence of periungual telangiectases or malar erythema. The patient admitted to sleeping on a heating pad because of a back injury in the weeks before her visit.

The rightsholder did not grant rights to reproduce this item in electronic media. For the missing item, see the original print version of this publication.

Question

Based on the patient's history and physical examination, which one of the following is the most likely diagnosis?

Discussion

The answer is C: erythema ab igne. Erythema ab igne represents a skin reaction to thermal injury.1 Typically, the affected area has a net-like pattern of blue-gray discoloration, sometimes with associated erythema and scale. Patients often complain of burning or pruritus of the involved area. The mainstay of treatment is avoidance of the heat source. Chronic heating pad use and warming in front of a wood-burning stove are common causes of erythema ab igne. Use of a laptop computer is a more modern source of this disorder.2 The discoloration slowly resolves over months to years; however, permanent scarring and hyperpigmentation can occur.

Discoid lupus erythematosus is a chronic inflammatory disease consisting of fixed, atrophic, erythematous papules and plaques that often are distributed on the head and neck.3 Pigmentary changes, hyperpigmentation and hypopigmentation, may be associated with discoid lupus erythematosus, as is extensive scarring. Epidermal changes include dilated (patulous) pores, prominent scale, and keratotic follicular plugging.

The lesions of systemic cutaneous lupus erythematosus consist of scaly, superficial, inflammatory macules, patches, and plaques that are classically photodistributed.3 Lesions of systemic cutaneous lupus erythematosus are annular or psoriasiform.

Erythema chronicum migrans typically is associated with Lyme disease caused by Borrelia burgdorferi.4 Approximately three fourths of patients with Lyme disease will develop erythema chronicum migrans.4 This starts as a small erythematous patch at the site of the bite and progresses to an annular erythema that may be 20 cm or more in diameter.

Livedo reticularis is a condition caused by dilation of capillary blood vessels and stagnation of blood within these vessels. Subsequently, a mottled discoloration of the skin occurs. It is described as a reticular, reddish blue, cutaneous discoloration surrounding a pale central area.5 This may be a marker of systemic conditions such as arterial embolic disease.

ConditionCharacteristics
Discoid lupus erythematosusHyperpigmented patches or plaques, often with hypopigmented areas; typically involves sun-exposed areas
Systemic cutaneous lupus erythematosusErythematous papulosquamous patches on photo distributed areas mainly on upper body
Erythema ab igneMottled and reticulated nonblanching erythematous patches; usually in localized area corresponding to exposure to a nonburning heat source
Erythema chronicum migransErythematous patch with expanding annular erythema; possible history of tick bite
Livedo reticularisReticulated erythema on extremities with red and blue coloration

The editors of AFP welcome submissions for Photo Quiz. Guidelines for preparing and submitting a Photo Quiz manuscript can be found in the Authors' Guide at https://www.aafp.org/afp/photoquizinfo. To be considered for publication, submissions must meet these guidelines. E-mail submissions to afpphoto@aafp.org.

This series is coordinated by John E. Delzell Jr., MD, MSPH, associate medical editor.

A collection of Photo Quiz published in AFP is available at https://www.aafp.org/afp/photoquiz

Continue Reading


More in AFP

More in Pubmed

Copyright © 2006 by the American Academy of Family Physicians.

This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP.  See https://www.aafp.org/about/this-site/permissions.html for copyright questions and/or permission requests.