February 2007

A 13-month-old girl presents with eczematous papules of the right flank and axillae. The eruption spreads later to the right leg and then the rest of the trunk. The eruption was present for two days.

What's your diagnosis?

1. Unilateral laterothoracic exanthem
2. Atopic dermatitis
3. Seborrheic dermatitis
4. Erythema infectiosum

Answer

The answer is A, unilateral laterothoracic exanthem, also known as asymmetrical periflexural exanthem of childhood. The rash was first reported in 1962. It usually occurs in children and reports of the rash in adults are rare.

The rash manifests as eczematous papules of unilateral axilla and flank, and then spreads to other areas of the body. This eruption is actually an unusual viral exanthem.

Treatment for the rash includes topical corticosteroids for inflammation, and antipruritics for itching.

For more information:

• Chuh A, et al. Unilateral mediothoracic exanthem: a variant of unilateral laterothoracic exanthem. Cutis. 2006;77:29-32.
• Gutzmer R, et al. Unilateral laterothoracic exanthem (asymmetrical periflexural exanthem of childhood): report of an adult patient. J Am Acad Dermatol. 1997;37:484-485.