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7-year-old girl presents to ED with 1-day history of rash
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A 7-year-old girl presented to the ED with a 1-day history of a rash. The patient’s mother first noticed a spot on the right arm when she was drying the patient off after her bath, and she winced in pain as the towel moved over the area. The patient’s mother noted some redness and crusted erosions. The next day, when the area had not healed and the patient had new spots, the patient was brought to the ED.
No one else at home reported any rashes. The patient denied any injury to the areas but reported that they were tender. The family denied any application of any topical products to the areas. The patient had no fevers or other systemic symptoms, nor had she taken any oral medications.
Source: Marissa J. Perman, MD
On exam, the patient had several superficial crusted erosions on the right arm with thin peeling at the edges (Figure 1), as well as three circular flaccid bullae on the right medial knee (Figure 2). There were several smaller flaccid bullae, as well as superficial and crusted erosions on the bilateral dorsal fingers. A complete skin examination revealed no other lesions.
Can you spot the rash?
A. Stevens-Johnson syndrome
B. Bullous impetigo
C. Pemphigus foliaceus
D. Nonaccidental trauma
E. Herpes simplex
Case Discussion
Impetigo is the most common primary cutaneous infection in children. It is most commonly caused by Staphylococcus aureus and group A beta-hemolytic Streptococcus pyogenes. Bullous impetigo (B) is primarily caused by specific strains of S. aureus (phage group 2, types 55 and 71) that produce exfoliative toxins. These toxins form superficial blisters by targeting desmoglein 1 in the subcorneal layer of the epidermis. Nonbullous impetigo typically causes crusted, erythematous plaques with a characteristic “honey” color.
Intact vesicles and bullae are rarely seen in bullous impetigo given their fragile nature but when present are flaccid. Instead, the disease is usually characterized by single or clustered, shallow erosions with collarettes of scale and minimal to no surrounding erythema. Both forms of impetigo favor the face, buttocks, groin, axillae, neck and extremities but can occur anywhere on the body. Lesions heal without scarring but leave behind postinflammatory hyperpigmentation that can last weeks to months. Impetigo is contagious and easily spread among contact sports participants and school children.
Bacterial cultures are imperative to guide appropriate therapy, although the diagnosis can be made clinically. Fluid from a vesicle, pustule or the area beneath the edge of a crusted plaque provides the highest yield for a positive culture. Skin biopsy should be performed only if the diagnosis is in question and shows a subcorneal pustule with mixed dermal inflammation. Bacteria may be seen in the crust but are not required for the diagnosis.
Localized forms of impetigo can be treated with topical antibiotics such as mupirocin, Altabax (retapamulin GlaxoSmithKline) or Xepi (ozenoxacin, Medimetriks Pharmaceuticals). Oral antibiotics may be required for more diffuse eruptions or resistant organisms. Antibiotics like cephalexin, cloxacillin or dicloxacillin should cover both penicillinase-resistant S. aureus and S. pyogenes. MRSA is usually not responsible for bullous impetigo, but empiric treatment with clindamycin may be considered based on local epidemiology of MRSA infection rates. However, MRSA resistance to clindamycin is increasing, and following culture sensitivities is important to ensure optimal treatment. In cases such as infants or others in whom bullous impetigo can progress rapidly, IV antibiotics may be required.
The differential diagnosis of bullous impetigo includes pemphigus foliaceus, pemphigus vulgaris, eczema herpeticum, rhus (poison ivy) dermatitis, herpes simplex virus infection, nonaccidental trauma, and linear IgA bullous dermatosis. Pemphigus foliaceus is an autoimmune bullous disorder that targets desmoglein 1, the same molecule cleaved in bullous impetigo.
Skin lesions are one of the most common presentations of child abuse or nonaccidental trauma (NAT). Skin lesions that have a geometric appearance, have a delay in presentation to care or a story inconsistent with the physical exam should include NAT in the differential. The circular nature of the scaldlike lesions of bullous impetigo can be confused for cigarette or other burns. The presence of lesions with variable sizes and typical sites of involvement can aid in the correct diagnosis and avoid false accusations of child abuse.
Bullous impetigo is a common superficial bacterial skin infection with erosions and crusting often on the face, diaper area, and extremities. Early recognition can expedite appropriate workup and treatment.
- References:
- AlJasser M, Al-Khenaizan S. Eur J Pediatr. 2008;doi:10.1007/s00431-008-0792-0.
- Eichenfield LF, et al. Neonatal and Infant Dermatology. 3rd ed. London: Elsevier; 2015.
- Koch E, et al. Pediatr Dermatol. 2016;doi:10.1111/pde.12982.
- Paller AS, et al. Hurwitz Clinical Pediatric Dermatology: A Textbook of Skin Disorders of Childhood and Adolescence. 5th ed. London: Elsevier; 2016.
- For more information:
- Colleen H. Cotton, MD, is a pediatric dermatology fellow at The Children’s Hospital of Philadelphia. She can be reached at CottonCH@email.chop.edu.
- Marissa J. Perman, MD, is an attending physician at The Children’s Hospital of Philadelphia.
Disclosures: Cotton and Perman report no relevant financial disclosures.