Rash, Pediatric

Rash, Pediatric is a topic covered in the 5-Minute Emergency Consult.

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  • Lesion morphology:
    • Macule:
      • Localized nonpalpable changes in skin color
      • Purpura or petechiae (nonblanching with pressure)
    • Maculopapule:
      • Slightly elevated lesions with localized changes in skin
    • Papule:
      • Solid, elevated lesions <5 mm in diameter
      • Keratotic (rough-surfaced lesion)
      • Nonkeratotic (smooth lesion)
      • Palpable purpura (nonblanching with pressure)
    • Plaque:
      • Solid, elevated lesions >5 mm in diameter
      • Often results from a confluence of papules
    • Nodule:
      • Solid, elevated lesions extending deep into the dermis or SC tissue >5 mm in diameter
    • Wheal:
      • Circular, irregular lesions varying from red to pale
    • Vesicle:
      • Clear, fluid-filled lesions <5 mm in diameter
    • Bullae:
      • Clear, fluid-filled lesions >5 mm in diameter
    • Pustules:
      • Pus-filled lesions
  • Secondary lesions:
    • Scales:
      • Thin plates of dried cornified epithelium partially separated from the epidermis
    • Lichenification:
      • Dried plaques resulting in skin furrowing
    • Erosion:
      • Moist surface uncovered by rupture of vesicles or bullae
    • Excoriation:
      • Linear loss of the skin due to trauma
    • Ulcer:
      • Deep loss of the skin involving the epidermis and a variable amount of the dermis and SC tissue
  • Configuration:
    • Circles or arcs
    • Serpiginous (creeping or worm like)
    • Iris grouping (bull's eye appearance)
    • Irregular grouping
    • Zosteriform grouping
    • Linear grouping
    • Retiform grouping
  • The color of a lesion or the entire skin may be due to a number of substances:
    • Red or red-brown lesions result from oxyhemoglobin found in RBCs.
    • The macular erythematous lesions seen in viral exanthema usually represent dilated superficial cutaneous vessels.
    • Purpura and petechiae result from leakage of RBCs out of the vascular space.
    • Hypopigmentation or hyperpigmentation represent postinflammatory change from either increases or decreases in melanin production.
    • Depigmentation refers to the total loss of pigment secondary to autoimmune effect (vitiligo) or congenital disorders (albinism).
  • Scales represent a proliferative disorder of epidermal cell turnover.


  • Papulosquamous:
    • Infections:
      • Viral or bacterial
      • Rickettsial or fungal
    • Allergic reactions
    • Autoimmune disorders
  • Purpura and petechiae:
    • Clotting or platelet disorder
    • Vascular fragility disease
    • Vasculitis
    • Overwhelming infection
  • Vesicobullous:
    • Infection
    • Drug reaction
    • Autoimmune disorder
  • Ulcer:
    • Infection
    • Vascular insufficiency

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