Approach

• History
  • SOCRATES
  • Family/friends with similar rash
  • Medication
  • Household products
• Examination
• Investigation

Differential Diagnosis

• Roseola infantum (exanthema subitum)
• Pityriasis rosea
• Scarlet fever
• Impetigo
• Erythema infectiosum
• Molluscum contagiosum
• Tinea infection
• Atopic dermatitis

Distribution

• Erythematous exanthems that tend to start on the face
  • Measles
  • Rubella
  • Erythema infectiosum
• Erythematous exanthems that tend to start on the trunk
  • Roseola
  • Scarlet fever
  • Unilateral laterothoracic exanthem
• Papulo-vesicular exanthems
  • Chickenpox (syn. varicella)
  • Gianotti-Crosti syndrome
• Exanthems of the extremities
  • Hand, foot and mouth disease
  • Papular-purpuric gloves and socks syndrome

Roseola Infantum (Exanthema Subitum)

• Herpsevirus 6 and 7

Scarlet fever

• Group A Strep
• Staphlococcus pyogenes

Impetigo

• Staphylococcus
• Bullous
• Non-bullous (crusted)