Erythema Infectiosum and Acropustulosis of Infancy

Case 1:

This young girl is brought to your office with a rash that her mother thinks is triggered by sunlight. The mother is concerned because her own aunt has lupus erythematosus. The mother also reports that several children at her daughter's school have a similar eruption.

What's going on?

Case 2:

This baby has experienced repeated outbreaks of "scabies" that have been resistant to treatment. Why has she not responded?

Case 1: This young girl has erythema infectiosum--or fifth disease. Typically, the initial presentation is a bright erythema of both cheeks, which conferred the popular name of "slapped cheek" disease. The cutaneous signs may be preceded by mild constitutional symptoms, such as fever and malaise. Within a few days of the appearance of the slapped cheeks, a reticulate erythema appears on the arms and trunk (B). This "patterned" erythema is evanescent, lasts for weeks to months, and is usually exacerbated by sunlight or warm baths.

The slapped-cheek presentation is easy to recognize. It is the reticulate erythema that puzzles practitioners if the child is seen after the cheeks have cleared or if the cheek erythema was minimal.

The child presented in this case was referred to me for the evaluation of photosensitivity because the rash on her arms developed after outdoor play and improved overnight. The provisional diagnosis was lupus erythematosus, based on her family history. The defining clue to the diagnosis of fifth disease was the history of a facial rash that had affected many children in her school during the past month.

Erythema infectiosum is the result of infection with parvovirus B19 that occurs in the winter and spring. In the community, it spreads by respiratory droplets and has an incubation period of about 4 to 14 days. The infection occurs worldwide. By the time the reticulate rash has appeared, the viremia has cleared and the child is no longer infectious. A self-limited arthralgia develops in about 10% of affected children.

Be sure to warn mothers of infected children of the risks if they are pregnant and become infected with parvovirus B19. The risk of fetal loss is between 5% and 10%--particularly if the infection occurs in the first 12 to 20 weeks of gestation. Fortunately, 60% of adults are immune to this virus. In this situation, I consider testing for serum anti-B19 antibody to assess the mother's immune status.

Children who have chronic hemolytic anemia may experience an aplastic crisis with parvovirus B19 infection. Keep this possibility in mind during follow-up.

Case 2: This baby has acropustulosis of infancy (AI). This condition is often confused with infantile scabies, and it may take multiple negative skin scrapings to confirm the diagnosis. To complicate the problem in distinguishing this condition from infantile scabies, AI may be preceded by an actual scabies infestation that has been adequately treated.

The initial episode of AI generally presents in the first few months of life as multiple crops of vesiculopustules that appear on the hands and feet and that mimic infantile scabies. Those most commonly affected are black male infants; however, the condition does occur in both sexes and in other races. The lesions occur in an "eruptive pattern," with episodes that occur every few weeks. Each episode lasts 5 to 7 days over 1 to 2 years. Individual lesions are intensely pruritic. They are predominately located on the palms and sole, with occasional extension onto the dorsa of the hands and shafts of the fingers and toes.

The skin scrapings performed to rule out scabies show multiple neutrophils without evidence of scabies infestation. If one needs a skin biopsy to confirm the diagnosis, the histopathology will reveal intraepidermal vesiculopustules that are rich in neutrophils and eosinophils.

The first trial of therapy should be with superpotent topical corticosteroids applied twice daily to the involved area. If this treatment is successful, I ask parents to apply the medication at the first sign of itching (which usually precedes the eruption of skin lesions). These steroids will produce significant atrophy of the skin. Parents must be educated about this effect, but they also need to be encouraged to use the medication when it is needed. Systemic antihistamines, such as hydroxyzine, may also be helpful.

If these measures do not help, therapy with systemic dapsone (1 mg/kg/d) may be beneficial.

Episodes of AI tend to develop less frequently and with less intensity over time. The natural history of this condition is to spontaneously remit within the first 2 to 3 years of life without sequelae. *