Vesiculobullous rashes


  • Vesiculobullous disorders characterized by involvement of the dermal-epidermal junction (causing fluid-filled lesions to form)

Rash Red Flags[1]

  • Fever
  • Toxic appearance
  • Hypotension
  • Mucosal lesions
  • Severe pain
  • Very old or young age
  • Immunosuppressed
  • New medication

Dermatology Nomenclature

Small lesions (<0.5cm)

  • Macule – flat, cirumscribed, colored, non palpable
  • Papule – raised, solid and palpable
  • Vesicle – raised, palpable, clear fluid-filled
  • Pustule – raised, palpable, pus filled (leukocytes or keratin)

Large lesions (>0.5cm)

  • Patch – large macule (flat non-palpable colored area)
  • Plaque – superficially raised, circumscribed solid area
  • Nodule – distinct large papule
  • Bulla - large vesicle (blisters if epidermal layer completely sloughed off)
  • Wheal – firm and edematous plaque (edema of the dermis)


  • Plaque/scaley papule
  • Eschar
  • Erosion/ulcer
  • Purpura/petechia
  • Plaque/smooth papule

Clinical Features

  • Vesicles are small (<1cm)
  • Bullae are larger (>1cm)

Vesiculobullous rashes visual diagnosis

Differential Diagnosis

Vesiculobullous rashes




  • Frequently a clinical diagnosis based on ruling-out more dangerous causes
  • See differential diagnosis section (above)
    • Consider whether or not the patient has a fever or is toxic appearing (dangerous diagnosis)
    • Look at lesion distribution


  • Based on presumed cause


  • Based on presumed cause

See Also


  1. Nguyen T and Freedman J. Dermatologic Emergencies: Diagnosing and Managing Life-Threatening Rashes. Emergency Medicine Practice. September 2002 volume 4 no 9.