Impetigo
Epidemiology:
- Healthy children
- Unhealthy adults
Common sites:
Gross features:
- erythematous macule
(early)
- multiple small
pustules (later)
- shallow erosions
covered by drying serum (characteristic honey-coloured
crust) (even later)
Histologic features:
- neutrophils beneath the stratum corneum
- bacteria present
on special stains
- reactive epidermal
changes
- superficial dermal
inflammation
- crust composed of
serum, neutrophils, and cellular debris
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
Other features:
- Staphylococcus aureus
in most cases
- Group A
Beta-hemolytic streptococci used to cause impetigo contagiosa
- Bacterial production
of a toxin that specifically cleaves desmoglein
1 (cell-to-cell adhesion in uppermost epidermal layers)
References: