Two cases of asymmetric papules
Both of these young patients presented with rashes that had spread from their abdomen to their arms and legs—but only on one side.
Dx: Asymmetric periflexural exanthem of childhood
Both of these patients were given a diagnosis of asymmetric periflexural exanthem of childhood (APEC), based on the appearance and distribution of the rashes.
A rare condition that mostly affects young children
APEC is a rash of unknown cause, although epidemiologic and clinical findings support a viral etiology. Cases of this rash were first reported in 1992 by Bodemer et al, and a year later, Taïeb et al reported new cases, establishing the term “asymmetric periflexural exanthem.”1,2 Several viruses have been related to APEC (including adenovirus, parvovirus B19, parainfluenza 2 and 3, and human herpesvirus 7), but none of these has been consistently associated with the rash.3-5
APEC tends to affect children between one and 5 years of age, but adult cases have been reported.6,7 The condition occurs slightly more frequently among females and more often in winter and spring.8,9 APEC is a rare condition; since 1992, there have only been about 300 cases reported in the literature.10
What you’ll see. The erythematous rash appears as an asymmetrical or unilateral papular, scarlatiniform, or eczematous exanthema. It initially affects the axilla or groin and may then progress to the extremities and trunk. Minor lesions infrequently present on the contralateral side. Most children who are affected by APEC are otherwise healthy and asymptomatic at presentation. The exanthem is occasionally pruritic and can be preceded by short respiratory or gastrointestinal prodromes or a low-grade fever.2,9 If the rash predominantly affects the lateral thoracic wall, it may be referred to as unilateral laterothoracic exanthem.11 Regional lymphadenopathies can often be found, and there is no systemic involvement.
