Impetigo Differential Diagnosis

The following differential diagnosis is organized into categories to help guide the thought process:

• Single most likely diagnosis
  • Eczema (atopic dermatitis): This is often considered due to the similar appearance of skin lesions and the commonality of eczema in the population. However, eczema typically has a more chronic course and is associated with intense itching.
• Other Likely diagnoses
  • Contact dermatitis: This condition can present with similar skin lesions and is caused by an allergic reaction or irritation from substances in contact with the skin.
  • Folliculitis: An infection of the hair follicles, which can present with pustules or crusts similar to impetigo, especially if caused by Staphylococcus aureus.
  • Scabies: A parasitic infection caused by the mite Sarcoptes scabiei, which can lead to skin lesions and intense itching, though the distribution and presence of burrows can help differentiate it.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Cellulitis: A bacterial infection of the skin and subcutaneous tissues that can spread rapidly and lead to serious complications if not treated promptly. It often presents with redness, swelling, and warmth of the skin.
  • Erysipelas: A type of superficial cellulitis caused by Streptococcus bacteria, characterized by a well-demarcated, raised, and fiery red area of the skin.
  • Necrotizing fasciitis: A severe infection of the fascia, the tissue that surrounds muscles, nerves, fat, and blood vessels in the affected area. It is a medical emergency.
• Rare diagnoses
  • Pemphigus: A group of rare skin disorders that cause blistering of the skin and mucous membranes. It is an autoimmune disease that can be life-threatening if not treated.
  • Bullous impetigo: Though a form of impetigo, it's caused by specific strains of Staphylococcus aureus that produce exfoliative toxins, leading to bullae formation.
  • Staphylococcal scalded skin syndrome (SSSS): A condition caused by staphylococcal toxins that typically affects infants and young children, leading to widespread blistering and peeling of the skin.

Each of these diagnoses has distinct features that can help in differentiating them from impetigo, but considering them in the differential diagnosis is crucial for appropriate management and to avoid missing potentially serious conditions.