Originally published at Pediatric EM Morsels on November 17, 2017. Reposted with permission.

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Childhood rashes are not my favorite topic or condition to contemplate. I use a rather simplistic approach (see Approach to Rashes) and a little bit of knowledge about typical childhood dermatologic eruptions (ex, Molluscum, Diaper Dermatitis, Perianal Strep, Scabies, Erythema Multiforme). Sometimes, though, things can get a little weird (ex, pyoderma gangrenous). Additionally, the child’s own skin conditions can influence the appearance of typical conditions (like Atopic Dermatitis -> Eczema Herpeticum). Another condition to add to that unique list is Hand Foot Mouth Disease. Let’s look at Severe Hand Foot Mouth Disease:

Hand Foot Mouth Disease: Classic

• Hand Foot Mouth Disease (HFMD) classically is associated w/:
  • Stomatitis of the oral mucosa – small vesicles and erosions in the mouth
  • Vesicles on the hands, feet, and occasionally the buttocks
  • Fever
  • Mild gastrointestinal symptoms
  • Known sick contracts

• It is associated with enterovirus.

Hand Foot Mouth Disease: Severe

• Severe forms of HFMD have been found to present in atypical fashions. [Mathes, 2013]
  • Associated with Coxsackievirus A6
  • Occur in outbreaks.

• It can present in 4 other distinct manners: [Mathes, 2013]
  1. Widespread vesicles, bullae, and erosions that extend beyond palms and soles
     • Perioral, acral, and buttock areas are predominant
     • Younger children (<1 year) are more likely to have bullae.
  2. “Eczema Coxasckium” – Eczema herpeticum-like eruption
     • Vesicles and erosions occurring in areas where eczema is present.
     • Eruptions are thought to be more prominent in areas of skin/mucosal“trauma”… so hands, feet, mouth… and that may explain why eczema leads to wider distribution. [Mathes, 2013]
  3. Gianotti-Crosti – like eruption
     • Acro-fascial papules, vesicles, and erosions
     • Spares the truck.
  4. Petechiae or purpura
     • Seen in older children (>5 years)
     • Often acral (involving the extremities)

Severe HFMD: The DDX

• There are several mimics of severe HFMD.
• Some notable ones include:
  • Bullous impetigo
  • Varicella
  • Immunologic disorders
  • Secondary bacterial infection of eczema
  • Urticaria multiforme
  • Vasculitis
  • Eczema herpeticum
  • Gianotti-Crosti syndrome [Chuh, 2016]
    • Monomorphic, papular eruptions in symmetric, acral distribution.
    • Also seen on face and buttock.
    • Associated with coxsackie virus (as well as, HBV, EBV, CMV, enterovirus, and HSV).
    • Also associated with atopic dermatitis!

• If unsure, and testing is warranted, consider:
  • Enterovirus PCR testing of vesicle fluid (check with your lab for its specific requirements).
  • Viral culture for Coxsackievirus A6 is NOT recommended as it does not grow well in culture.
  • Also consider HSV culture or direct fluorescent antibody testing in patient with vesicular/bullous disease.

Moral of the Morsel

• Not all severe appearing rashes are life-threatening. Be careful, but know the Ddx.
• Once again, a virus can cause lots of concern. Don’t say “It’s just a virus.”
• Keep unusual presentation of common conditions on your Ddx.

References