Are You Confident of the Diagnosis?
What you should be alert for in the history
Unilateral laterothoracic exanthem (ULE) usually presents in a healthy child who is generally asymptomatic. Patients may report preceding vague constitutional symptoms such as a low grade fever, upper respiratory symptoms or gastrointestinal symptoms. The prodrome is usually within days to weeks of the onset of the exanthem. Mild pruritus may be present in more than 50% of patients.
Characteristic findings on physical examination include
Initial phase: The rash is unilateral, most commonly localized to the lateral thorax, particularly near the axilla or other periflexural areas such as the inguinal area. Typical lesions are small, erythematous and usually eczematous papules surrounded by a pale halo, but the morphology may be variable. When examining the patient asking them to show the rash, one arm only is raised – this has been affectionately referred to as the ’Statue of Liberty’ sign (Figure 1).
In the first week, the exanthem spreads centrifugally. At this point, it may also take on a more inflammatory or annular appearance. Eventually, the eruption becomes more confluent and evolves to appear more morbilliform or eczematous.
Secondary phase: In the second to third week, the rash may spread to involve the contralateral side. The rash always tends to remain asymmetrical favoring the initial side of involvement however.
Resolving phase: Lesions may become dusky appearing and eventually desquamate.
Expected results of diagnostic studies
Diagnostic studies are generally not indicated as the diagnosis is made on a clinical basis.
The differential diagnosis includes papular eczema, contact dermatitis with an eczematid reaction, Gianotti-Crosti syndrome, atypical pityriasis rosea, and dermatophyte infection.
Who is at Risk for Developing this Disease?
ULE almost exclusively occurs in children. The average age of onset is 2 years old. A greater number of females than males are affected. ULE mostly occurs in winter and spring.
What is the Cause of the Disease?
The cause is unknown. A viral etiology is suspected. Case reports have suggested possible association to Epstein-Barr and parvovirus B19.
Systemic Implications and Complications
No systemic complications have been associated with ULE.
No specific treatment is indicated for ULE.
For pruritus use:
Topical steroids (Hydrocortisone 2.5% Ointment or Triamcinolone 0.1% Ointment). Note: Mild to mid-potency topical steroids should be used cautiously to avoid increased absorption in periflexural locations and therefore potential side effects of atrophy, striae and telangiectasias.
Anti-histamines (Diphenhydramine, Hydroxyzine)
Optimal Therapeutic Approach for this Disease
This is a self-limited disease that requires no specific treatment. If the patient is symptomatic, then treatment options include emollients, topical steroids and anti-histamines.
ULE is self-limited and resolves spontaneously within 4-6 weeks. No long term follow-up is generally necessary.
Unusual Clinical Scenarios to Consider in Patient Management
Recurrent episodes have rarely been reported. Adult cases have been reported.
What is the Evidence?
Brunner, MJ, Rubin, L, Dunlap, F. “A new papular erythema of childhood”. Arch Dermatol. vol. 85. 1962. pp. 539-40. (The original work describing LE)
Bodemer, C, de Prost, Y. “Unilateral laterothoracic exanthem in children: a new disease?”. J Am Acad Dermatol. vol. 27. 1992. pp. 693-6. (A case series that describes the original course of 18 children with ULE. These authors were the first to propose the term “unilateral laterothoracic exanthem”.)
Taieb, A, Megraud, F, Legrain, V, Mortureux, P, Maleville, J. “Asymmetric periflexural exanthem of childhood”. J Am Acad Dermatol. vol. 29. 1993. pp. 391-3. (A follow-up case series of patients with ULE, but further describing the natural history of the disease suggesting a likely viral etiology. The authors proposed the terminology “asymmetric periflexural exanthem of childhood”.)
Laur, WE. “Unilateral laterothoracic exanthem in children”. J Am Acad Dermatol. vol. 29. 1993. pp. 799-800. (One of the larger case series reporting ULE.)
Harangi, F, Varszegi, D, Szucs, G. “Asymmetric periflexural exanthem of childhood and viral examinations”. Pediatr Dermatol. vol. 12. 1995. pp. 112-5. (The largest case series describing ULE. As with other studies, the authors suggested an infectious (likely viral) etiology, but no specific etiologic agent could be established.)
Coustou, D, Leaute-Labreze, C, Bioulac-Sage, P, Labbe, L, Taieb, A. “Asymmetric periflexural exanthem of childhood: a clinical, pathologic, and epidemiologic prospective study”. Arch Dermatol. vol. 135. 1999. pp. 799-803. (A case series that showed that interhuman transmission was not identifiable. Also identified that an association with pityriasis rosea was not likely.)
Coustou, D, Masquelier, B, Lafon, ME, Labreze, C, Roul, S, Bioulac-Sage, P. “Asymmetric periflexural exanthem of childhood: microbiologic case-control study”. Pediatr Dermatol. vol. 17. 2000. pp. 169-73. (A case-controlled study that showed that no specific microbiologic agent could be identified as an etiologic agent of ULE.)
Duarte, AF, Cruz, MJ, Baudrier, T, Mota, A, Azevedo, F. “Unilateral laterothoracic exanthem and primary Epstein Barr virus infection: case report”. Pediatr Infect Dis J. vol. 28. 2009. pp. 549-50. (Most recent case report suggesting a possible etiologic role of EBV in ULE.)
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