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Unilateral laterothoracic exanthem of childhood in Child
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Unilateral laterothoracic exanthem of childhood in Child

Contributors: Hannah Song BA, Keith Morley MD, Jennifer Huang MD, Susan Burgin MD
Other Resources UpToDate PubMed


Unilateral laterothoracic exanthem (ULE), also known as asymmetric periflexural exanthem of childhood, is a self-limited, likely reactive process to a viral infection commonly seen in infancy and early childhood.

The clinical presentation includes a mildly pruritic eczematous or morbilliform rash that typically presents in a unilateral, localized distribution on the trunk and/or extremities. The eruption can spread to involve the contralateral side in 65%-70% cases over 2-4 weeks, but the rash usually remains more prominent on the initial affected side. The eruption can develop a more eczematous quality before resolving with fine, superficial desquamation. Associated symptoms include fever and pruritus. The mean time for resolution is 5 weeks, and recurrence is unusual.

ULE affects children who are 2-3 years of age (although it has been described in children 8 months to 10 years of age) with a 2:1 female-to-male predominance. It is usually seen in the winter and spring seasons. There may be a preceding history of fever or other symptoms of upper respiratory or gastrointestinal illness.

There are reports of family members concomitantly affected with a similar rash, which is suggestive of an infectious etiology. However, a study investigating a large panel of bacterial and viral agents in patients with ULE was unable to identify a single etiologic agent.

There is no association between ULE and immunocompromised states or malignancy. There is one reported case of ULE in a child with acute lymphoblastic leukemia. The exanthem followed the typical clinical course, although it lasted for 4 months, and did not require either delay or cessation of oncologic therapy.


B09 – Unspecified viral infection characterized by skin and mucous membrane lesions

49882001 – Viral exanthem

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Differential Diagnosis & Pitfalls

  • Acute Allergic contact dermatitis  – Pruritic papules and vesicles superimposed upon an erythematous base a few days to weeks after skin contact with an allergen, contingent upon whether area was previously exposed to allergen. The distribution may be linear or otherwise geometric but varies with the area of exposure.
  • Nonspecific Viral exanthem – Similar to ULE in history and physical exam, and may be on the same spectrum as ULE. The asymmetry of ULE is the distinguishing feature.
  • Gianotti-Crosti syndrome – More diffuse or edematous papular exanthem occurs more prominently over the face, buttocks, and extensor surfaces of the extremities following a viral infection, and is not limited to one side.
  • Atopic dermatitis – Eczematous plaques and associated pruritus may mimic ULE, but atopic dermatitis should be more symmetric in distribution and more chronic in clinical course.
  • Seborrheic dermatitis – Dry to greasy scale and erythematous patches in flexural regions that are less likely to be unilateral in distribution.
  • Tinea corporis – Annular or oval erythematous plaques with central clearing and scaly border in children who are in frequent contact with domestic animals and/or play contact sports.

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Last Reviewed:03/08/2017
Last Updated:03/09/2017
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Unilateral laterothoracic exanthem of childhood in Child
A medical illustration showing key findings of Unilateral laterothoracic exanthem of childhood : Asymmetric trunk or extremity distribution, Scaly papule, Smooth papule, Unilateral distribution, Pruritus
Clinical image of Unilateral laterothoracic exanthem of childhood - imageId=278109. Click to open in gallery.  caption: 'Erythematous papules and plaques, some with a retiform configuration, on the trunk and arm.'
Erythematous papules and plaques, some with a retiform configuration, on the trunk and arm.
Copyright © 2024 VisualDx®. All rights reserved.