What is eczema coxsackium?
Eczema coxsackium is an enteroviral infection typically affecting children with atopic dermatitis (eczema). It is characterised by an eruption of vesicles, bullae, and erosions affecting areas of active or inactive atopic dermatitis.
Eczema coxsackium is a form of Kaposi varicelliform eruption, and has been described as atypical hand, foot and mouth disease (HFM). Both conditions are caused by enterovirus. However, eczema coxsackium is more widespread than hand, foot and mouth disease, and presents with vesiculobullous lesions that ulcerate and scab. The term eczema coxsackium was coined by Nahmias et al in 1968 .
Who gets eczema coxsackium?
Eczema coxsackium most commonly affects preschool-age children with atopic dermatitis . It affects both boys and girls, and typically presents during late spring to early summer [3–4]. There have been reported cases in adults [2,5].
Enteroviral infection can also localise to sites of epidermal barrier breakdown that are not caused by eczema. Reported cases of non-eczematous conditions prone to enteroviral infection include [2,5–8]:
- Irritant contact dermatitis (napkin dermatitis, thumb-sucking dermatitis, lip licker's dermatitis, and medication-induced dermatitis)
- Tinea pedis
- Darier disease
- Mosaic epidermolytic ichthyosis
What causes eczema coxsackium?
Coxsackievirus A6 and A16 are the most common causes of eczema coxsackium.
The reason why the enterovirus localises to sites with atopic dermatitis remains unclear. It is thought the mechanism is similar to eczema herpeticum, where afflicted patients appear to have impaired immunity to the virus and barrier dysfunction at the affected sites . This mechanism may explain how non-eczematous conditions such as Darier disease have also presented with a widespread viral infection that preferentially erupts at the sites of the skin disease .
What are the clinical features of eczema coxsackium?
Eczema coxsackium presents with vesicles, bullae, and erosions.
- The vesicles are relatively monomorphous and can be painful, but are generally not pruritic.
- Bullae are more common in infants under one year of age compared to older children, who present with vesicles .
- The vesicles and bullae can progress to erosions and scabs.
- Any site can be affected but hands, feet, face, torso, and buttocks/groin are usually involved.
- Lesions preferentially localise to sites affected by atopic dermatitis or another skin disease. Lesions may also be present on unaffected skin or skin previously affected by eczema.
- Oral ulcers can be present. These are less common than with hand, foot and mouth disease.
- Fever and oropharyngeal pain are common.
- The course of illness is similar to the classical hand, foot and mouth disease with no serious long-term sequelae.
How is eczema coxsackium diagnosed?
Reverse transcription-polymerase chain reaction (RT-PCR) sequencing of blister fluid, stool, and oropharyngeal swabs can be used to confirm the presence of enterovirus. Coxsackievirus is difficult to culture in vivo. Thus, viral culture is not useful and has a high likelihood of a false negative result.
What is the differential diagnosis for eczema coxsackium?
The main differential diagnosis for eczema coxsackium is eczema herpeticum.
- Eczema herpeticum due to herpes simplex tends to be itchier than eczema coxsackium and is less likely to have oral lesions.
- Bullous impetigo can also cause itchy blisters and bullae on areas of eczema. Typically, there is honey-yellow crusting with staphylococcal impetigo.
- A primary immunobullous disease is more generalised and does not preferentially affect areas of eczema.
What is the treatment for eczema coxsackium?
Eczema coxsackium self resolves and does not usually require hospital admission.
Whilst waiting for microbiological confirmation, oral antiviral therapy (eg, aciclovir or valaciclovir) can be prescribed to treat herpes simplex but enterovirus does not respond to this. Specific anti-enteroviral medications or vaccines for enterovirus are not currently available (2020).
Children can become dehydrated if they are not drinking due to painful oral ulcers and they may need admission for intravenous or nasogastric rehydration.
Non-medicated emollients are recommended to treat active eczema. Topical steroids are generally not recommended during the acute illness but can be reintroduced to treat the associated eczema once the child is afebrile.
What are the complications of eczema coxsackium?
Common complications during the convalescence phase of eczema coxsackium include desquamation of the palms and soles and nail changes.
Nail changes occur 1–2 months after the acute infection and include:
- Horizontal ridging that slowly grows out (Beau lines)
- Painless nail shedding (onychomadesis).
Unlike other enteroviral infections, multiorgan involvement is rare in children with cutaneous coxsackievirus A6/16 infection.
Does the child have to stay off school?
Numerous outbreaks of enterovirus have occurred worldwide. Enterovirus is highly infectious and easily spreads via vesicle fluid, respiratory secretions, and faecal-oral contamination. Children should be excluded from school until all blisters have dried up.
Good hand hygiene is paramount in preventing spread from other bodily secretions. Stools remain infectious for up to one month after the acute illness.