Hand-Foot-Mouth Disease Rash Characteristics
The hand-foot-mouth disease (HFMD) rash classically presents as painful papules and vesicles on the palms, soles, and oral mucosa, but recent outbreaks show extensive variants including widespread vesiculobullous eruptions, periorificial involvement, and atypical distributions that can mimic other viral exanthems. 1
Classic Presentation
The traditional HFMD rash has distinct features:
- Oral lesions: Painful vesicles and ulcerations affecting the mouth, palate, and pharynx, often appearing as sores 1
- Palmar and plantar involvement: Painful papules and blisters on the palms of hands and soles of feet 2, 1
- Vesicular morphology: Small, deep-seated vesicles that may be erythematous at the base 3
- Buttock involvement: Rash commonly extends to the buttocks and genital area 1
The rash typically accompanies mild fever and resolves spontaneously within 7 days without treatment 3.
Atypical and Severe Presentations
Recent outbreaks, particularly with Coxsackievirus A6, demonstrate a broader clinical spectrum:
- Widespread exanthema: 87.6% of confirmed cases show skin lesions beyond the classic hand-foot-mouth distribution, with 41.5% involving 5 or more anatomical sites including trunk, arms, and legs 4
- Vesicobullous and erosive eruptions: More extensive blistering than classic presentation 1
- Periorificial lesions: Perioral rash is specifically associated with CV-A6 infection 4
- Eczema coxsackium: Localization in areas of pre-existing atopic dermatitis 1
- Gianotti-Crosti-like lesions: Papular acrodermatitis pattern 1
- Petechial/purpuric eruptions: Less common variant 1
Key Distinguishing Features
Important clinical clues that help differentiate HFMD from other exanthems:
- Asymptomatic or mildly symptomatic lesions: Unlike many viral rashes, the vesicles may be painless, particularly in recurrent episodes 3
- No mucosal involvement in some cases: Atypical presentations may spare the oral mucosa entirely 3
- Distribution pattern: The combination of acral (hands/feet) and oral involvement is characteristic, though not always present 4
Late Sequelae
- Nail dystrophies: Onychomadesis (nail shedding) or Beau's lines can occur weeks after initial symptom onset 2, 3
- Palmoplantar desquamation: Peeling of palms and soles may develop in the subacute phase 1
Critical Differential Diagnosis Considerations
HFMD must be distinguished from other conditions causing palmoplantar rash:
- Enteroviral infections (including CV-A6, CV-A16, and enterovirus 71) are the confirmed causes 5
- Rocky Mountain Spotted Fever: Can involve palms and soles but presents with blanching pink macules evolving to petechiae, typically starting on ankles/wrists with centripetal spread 5
- Kawasaki disease: Shows erythema and edema of palms/soles with subsequent periungual desquamation at 2-3 weeks, but lacks vesicles 5
- Drug hypersensitivity reactions: Can cause palmoplantar involvement but lack the characteristic vesicular morphology 5
Common Pitfalls
- Dismissing widespread rash as "not HFMD": The disease spectrum now includes generalized vesicular exanthema that can be mistaken for other viral infections 4
- Assuming adult immunity: Adult cases occur with recent CV-A6 strains, likely through fecal-oral transmission in household settings 1
- Missing recurrent episodes: Although rare, HFMD can recur, often with milder presentation in subsequent episodes 3