Photo Quiz

A Mottled Rash on the Torso



FREE PREVIEW Log in or buy this issue to read the full article. AAFP members and paid subscribers get free access to all articles. Subscribe now.


FREE PREVIEW Subscribe or buy this issue. AAFP members and paid subscribers get free access to all articles.

Am Fam Physician. 2006 Nov 15;74(10):1765-1766.

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.

Question

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

A. Discoid lupus erythematosus.

B. Systemic cutaneous lupus erythematosus.

C. Erythema ab igne.

D. Erythema chronicum migrans.

E. Livedo reticularis.

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.

Selected Differential Diagnosis of a Mottled Rash

Condition Characteristics

Discoid lupus erythematosus

Hyperpigmented patches or plaques, often with hypopigmented areas; typically involves sun-exposed areas

Systemic cutaneous lupus erythematosus

Erythematous papulosquamous patches on photo distributed areas mainly on upper body

Erythema ab igne

Mottled and reticulated nonblanching erythematous patches; usually in localized area corresponding to exposure to a nonburning heat source

Erythema chronicum migrans

Erythematous patch with expanding annular erythema; possible history of tick bite

Livedo reticularis

Reticulated erythema on extremities with red and blue coloration

Selected Differential Diagnosis of a Mottled Rash

View Table

Selected Differential Diagnosis of a Mottled Rash

Condition Characteristics

Discoid lupus erythematosus

Hyperpigmented patches or plaques, often with hypopigmented areas; typically involves sun-exposed areas

Systemic cutaneous lupus erythematosus

Erythematous papulosquamous patches on photo distributed areas mainly on upper body

Erythema ab igne

Mottled and reticulated nonblanching erythematous patches; usually in localized area corresponding to exposure to a nonburning heat source

Erythema chronicum migrans

Erythematous patch with expanding annular erythema; possible history of tick bite

Livedo reticularis

Reticulated erythema on extremities with red and blue coloration

Author disclosure: Nothing to disclose.

REFERENCES

1. Page EH, Shear NH. Temperature-dependent skin disorders. J Am Acad Dermatol. 1988;18(5 pt 1):1003–19.

2. Bilic M, Adams BB. Erythema ab igne induced by a lap-top computer. J Am Acad Dermatol. 2004;50:973–4.

3. Callen JP. Collagen vascular diseases. J Am Acad Dermatol. 2004;51:427–39.

4. McGinley-Smith DE, Tsao SS. Dermatoses from ticks. J Am Acad Dermatol. 2003;49:363–96.

5. Lotti T, Ghersetich I, Comacchi C, Jorizzo JL. Cutaneous small-vessel vasculitis. J Am Acad Dermatol. 1998;39(5 pt 1):667–90.

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 http://www.aafp.org/afp/photoquizinfo. To be considered for publication, submissions must meet these guidelines. E-mail submissions to afpphoto@aafp.org.



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. Contact afpserv@aafp.org for copyright questions and/or permission requests.

Want to use this article elsewhere? Get Permissions


Article Tools

  • Print page
  • Share this page
  • AFP CME Quiz

Information From Industry

More in AFP

More in Pubmed

Navigate this Article