Bullous impetigo (pediatric) - Anogenital in
Bullous impetigo is a localized form of staphylococcal scalded skin syndrome caused by exfoliative toxins (A and B) released by (phage group II) Staphylococcus aureus. These toxins cleave desmoglein 1, resulting in superficial blisters locally at the site of infection. It is primarily seen in children, especially infants, who lack antibodies against exfoliative toxins, and only rarely occurs in teenagers or young adults. Infection is spread by direct contact with colonized or infected individuals. Staphylococcus aureus often colonizes the nares, umbilicus, nails, and eyes; approximately 5% of S aureus has exfoliative toxin.
Bullous impetigo initially presents as flaccid bullae, which then rupture, leaving round erosions that become crusted. Constitutional symptoms and fever are rare and mild, if they occur. The disease commonly affects the intertriginous areas, face, and extremities.
Outbreaks tend to occur during the summer months and in humid climates. Full resolution typically occurs within 2-6 weeks. Rare progression to staphylococcal scalded skin syndrome can occur.
In neonates, the infection often presents in the first 2 weeks of life. Sometimes, bullous impetigo may result in serious infections like osteomyelitis, septic arthritis, pneumonia, and septicemia.
L01.03 – Bullous impetigo
399183005 – Impetigo bullosa
- Varicella – Typically features polymorphic lesions in various stages: macules, vesicles, pustules, and crusting. Face, trunk, and proximal extremities are involved.
- Tinea cruris or tinea corporis (bullous)
- Stevens-Johnson syndrome – Characteristic target lesions (necrotic center surrounded by erythema and edema [pallor]) along with hemorrhagic crusting of the lips and conjunctiva. There may be associated systemic symptoms.
- Erythema toxicum neonatorum – Usually noticed in the first few days of life. The lesions are erythematous macules or urticarial plaques topped with a 1-2 mm papule or pustule that spontaneously resolves within 1-2 days.
- Transient neonatal pustular melanosis – Presents in the immediate postnatal period and is characterized by vesiculopustules without associated erythema. The pustules rupture easily, leaving behind hyperpigmented macules that may be surrounded by a characteristic collarette of scale.
- Staphylococcal scalded skin syndrome
- Bullous fixed drug eruption – Well-demarcated, circular or oval, erythematous patches that recur in the same site (usually lips and trunk) each time the offending drug is administered. Lesions characteristically heal with hyperpigmentation.
- Herpes simplex virus (HSV) infection – Tiny grouped vesicles on an erythematous base that rupture to form polycyclic erosions. Prodromal symptoms are usually present. The skin of the face and hands is commonly affected.
- Neonatal herpes simplex virus infection
- Bullous insect bite reactions – Linear, irregular streaks of dermatitis with vesiculation at the site of bite, often with a "kissing pattern."
- Scabies – Pruritic, erythematous papules and vesiculopustules on the intertriginous areas, face, genitalia, and palms and soles. Burrows may be present in the finger web spaces, flexor aspects of the wrists, axillae, umbilicus, nipples, buttocks, and penis.
- Cutaneous candidiasis affects the intertriginous areas, especially the groin and neck, in the form of confluent, erythematous patches with multiple small satellite pustules. Potassium hydroxide (KOH) test from a pustular lesion reveals budding spores and pseudohyphae that confirm Candida infection.
- Chronic bullous dermatosis of childhood – Tense (subepidermal) blisters in the groin, lower abdomen, back, and perioral region. The characteristic rosette-like vesicles resemble a cluster of pearls surrounding a central healing bulla.
- Contact dermatitis
- Poison ivy or oak dermatitis
- Burns (see thermal or electrical burn, burn marks of child abuse)
- Bullous pemphigoid
- Epidermolysis bullosa simplex
- Sexual abuse – Cases have been reported of bullous impetigo affecting the vulvar region, leading to confusion with possible sexual abuse.