Hand-Foot-and-Mouth Disease in Adults
Hand-foot-and-mouth disease (HFMD) affects adults with the same name but presents with more severe and atypical features compared to children, particularly when caused by Coxsackievirus A6.
Key Differences Between Adults and Children
Clinical Presentation
Adults with HFMD experience more severe and atypical manifestations compared to the classic pediatric presentation 1, 2. While children typically present with mild oral lesions and characteristic vesicles on hands and feet, adults infected with Coxsackievirus A6 demonstrate:
- Extensive vesicular eruptions that may involve the scalp, trunk, and limbs beyond the classic hand-foot distribution 3
- More pronounced inflammatory changes including dactylitis-like swelling of fingers 4
- Severe keratinocyte necrosis on histology, resembling drug-induced eruptions 2
- Delayed-onset complications including skin desquamation and nail dystrophy (onychomadesis) occurring weeks after initial infection 4
Pathogen Differences
The disease maintains the same name across age groups, but Coxsackievirus A6 has emerged as the predominant pathogen in adult cases since 2008, replacing the traditional Coxsackievirus A16 and Enterovirus 71 that predominantly affect children 1, 2, 3. This newer strain causes more exuberant disease in immunocompetent adults 4.
Clinical Recognition in Adults
Diagnostic Features
Look for this constellation of findings:
- Fever and constitutional symptoms (more prominent than in children)
- Maculopapular or vesicular rash extending beyond classic sites to include scalp, trunk, and extremities
- Oral ulcers (may be minimal or absent in atypical presentations) 3
- Palmoplantar involvement with inflammatory changes
- Recent exposure to children with HFMD (critical epidemiological clue) 5, 6
Histopathologic Characteristics
When biopsy is performed, expect 2:
- Massive keratinocyte necrosis with shadow cells
- Neutrophilic exocytosis and spongiosis
- Involvement of adnexal structures (follicles, sweat glands)
- Dense CD3+ T-cell infiltrate with strong granulysin expression (cytotoxic profile)
Risk Factors for Adult Infection
Close contact with infected children and poor hand hygiene are the primary risk factors 1. The disease spreads through fecal-oral, oral-oral, and respiratory droplet transmission.
Management Approach
Reassurance and Monitoring
The disease is self-limiting in immunocompetent adults, typically resolving within 1 week 3, 6. Management focuses on:
- Symptomatic treatment only (no specific antiviral therapy required)
- Active communication and close monitoring for complications 7
- Patient education about the benign, self-resolving nature despite dramatic appearance 6
When to Escalate Care
Monitor for severe complications (rare but documented):
- Extensive skin involvement suggesting severe cytotoxic reaction
- Signs of systemic involvement
- Immunocompromised patients require closer observation
Important Clinical Pitfalls
Do not dismiss adult patients with atypical rashes when there is exposure history to children with HFMD. The increasing prevalence of Coxsackievirus A6 means adult cases are becoming more common 4, 3.
Do not confuse with drug eruptions – the histologic similarity to severe drug reactions can lead to misdiagnosis 2. The epidemiological history of exposure to infected children is crucial.
Anticipate delayed complications – warn patients about possible nail changes and desquamation occurring 2-4 weeks after initial infection 4.
The geographic distribution and seasonality may differ between adult and pediatric cases, with adults showing distinct epidemiological patterns 1.