Differential Diagnosis for Impetigo

When considering a diagnosis of impetigo, it's crucial to differentiate it from other skin conditions that may present with similar symptoms. Here's a structured approach to the differential diagnosis:

• Single Most Likely Diagnosis
  • Eczema (Atopic Dermatitis): Often presents with itchy, inflamed skin that can become infected, resembling impetigo. The presence of a personal or family history of atopy (asthma, allergies) and the distribution of lesions (typically on the face, hands, feet, inside the elbows, and behind the knees) can help differentiate it.
• Other Likely Diagnoses
  • Contact Dermatitis: An allergic or irritant reaction to substances like soap, detergent, or certain metals, leading to skin inflammation and possible secondary infection. The history of exposure to potential allergens or irritants and the pattern of the rash can help in diagnosis.
  • Folliculitis: Inflammation of the hair follicles, often due to bacterial infection, which can present similarly to impetigo, especially if the impetigo is follicular-based. The presence of follicular papules or pustules is key to distinguishing it.
  • Herpes Simplex Virus (HSV) Infection: Can cause vesicular lesions that may resemble impetigo, especially in the primary infection phase. The presence of grouped vesicles and a history of similar outbreaks can aid in diagnosis.
• Do Not Miss Diagnoses
  • Cellulitis: A bacterial infection of the skin and subcutaneous tissues that can spread rapidly and lead to serious complications if not treated promptly. It typically presents with redness, swelling, warmth, and pain in the affected area, without the distinct border seen in impetigo.
  • Erysipelas: A type of superficial cellulitis caused by Streptococcus bacteria, characterized by a well-demarcated, raised edge. It's essential to differentiate it from impetigo due to its potential for more severe complications.
  • Necrotizing Fasciitis: A severe infection of the fascia, the tissue that separates soft tissue and muscle, which can be life-threatening. Early signs may resemble those of cellulitis or impetigo but rapidly progress to severe pain, swelling, and skin necrosis.
• Rare Diagnoses
  • Pemphigus: A group of autoimmune diseases that cause blistering of the skin and mucous membranes. While rare, it can present with skin lesions that might be confused with impetigo, especially in the early stages.
  • Staphylococcal Scalded Skin Syndrome (SSSS): Caused by staphylococcal toxins that typically affect infants and young children, leading to widespread skin exfoliation. It's crucial to consider in pediatric patients with suspected impetigo who rapidly deteriorate.

Each of these conditions has distinct features that can help in differentiating them from impetigo. A thorough clinical examination, detailed patient history, and sometimes laboratory tests are necessary to establish an accurate diagnosis and guide appropriate treatment.