Is hand, foot, and mouth disease (HFMD) related to eczema?

Relationship Between Hand, Foot, and Mouth Disease and Eczema

Hand, foot, and mouth disease (HFMD) and eczema are distinct conditions, but they can interact in a clinically significant way, particularly through a phenomenon called "eczema coxsackium" where HFMD presents atypically in patients with pre-existing atopic dermatitis.

Eczema Coxsackium: The Connection Between HFMD and Eczema

Eczema coxsackium is a recognized atypical presentation of HFMD that occurs specifically in patients with pre-existing atopic dermatitis. This condition has several important characteristics:

• HFMD virus (particularly Coxsackievirus A6) can infect areas of pre-existing eczematous skin 1
• The presentation resembles herpetic superinfection (eczema herpeticum), making diagnosis challenging 1, 2
• The rash may be more extensive and severe than typical HFMD 3
• The virus preferentially affects areas with compromised skin barrier function 2

Clinical Presentation of Eczema Coxsackium

When HFMD affects patients with atopic dermatitis, it presents with:

• Papules and umbilicated vesicles affecting eczematous areas 2
• Lesions predominantly in pressure areas and sites of previous atopic lesions 2
• More widespread distribution than classic HFMD 3
• Possible vesiculobullous exanthema that may mimic other serious skin conditions 3

Diagnostic Considerations

Diagnosing eczema coxsackium requires careful consideration:

• Clinical appearance may mimic eczema herpeticum, making laboratory confirmation essential 2
• PCR testing of vesicle fluid, pharyngeal exudate, or stool samples can confirm enterovirus infection 2
• Patch testing should be deferred if considering allergic contact dermatitis as a differential diagnosis 4
• Careful examination of lesion distribution and morphology is critical 3

Management Approach

Management of eczema coxsackium follows principles similar to both HFMD and eczema care:

1. Supportive care remains the mainstay of treatment for HFMD manifestations 1
2. Skin barrier protection through:
   • Application of fragrance-free, hypoallergenic moisturizers multiple times daily 4
   • Using the "soak and smear" technique for severe cases 4
   • Avoiding irritants that may worsen eczematous skin 5
3. Topical steroids for recalcitrant eczematous areas, limiting use to 2 weeks to avoid skin atrophy 4
4. Monitoring for complications such as secondary bacterial infection 4

Prevention Strategies

Prevention focuses on managing both conditions:

• Maintain good hand hygiene practices while avoiding excessive hand washing that can worsen dermatitis 5
• Apply moisturizers regularly to maintain skin barrier function 4
• Avoid known irritants that can exacerbate eczema 5
• Implement appropriate hygiene measures to prevent HFMD transmission 1

Important Considerations and Pitfalls

• Misdiagnosis is common - eczema coxsackium is frequently mistaken for eczema herpeticum 1, 2
• Overuse of topical steroids can damage skin barrier and potentially worsen outcomes 4
• Secondary bacterial infection may complicate both conditions 4
• Nail changes may follow HFMD after a latency period 1

Understanding the relationship between HFMD and eczema is essential for accurate diagnosis and appropriate management, particularly in children with atopic dermatitis who present with atypical vesicular eruptions.