Skin nontumor

Vesiculobullous and acantholytic reaction patterns

Impetigo contagiosa

Last author update: 1 June 2015
Last staff update: 11 November 2020

Copyright: 2002-2023,, Inc.

PubMed Search: Impetigo contagiosa [title]

Erin M. Carlquist, M.D.
Lauren N. Stuart, M.D., M.B.A.
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Cite this page: Carlquist EM, Gardner JM, Stuart LN. Impetigo contagiosa. website. Accessed September 21st, 2023.
Definition / general
  • Contagious superficial infection of skin
  • 2 types of impetigo: impetigo contagiosa (nonbullous impetigo) and bullous impetigo
  • Nonbullous impetigo comprises > 70% of all cases of impetigo (An Bras Dermatol 2014;89:293)
    • Primarily an endemic disease in school aged children but may occur in epidemics
  • In U.S., most common cause is currently Staphylococcus aureus
  • Previously, most common cause was group A streptococci, either alone or in association with S. aureus (Pediatr Dermatol 1987;4:185)
  • Infection with resistant strains, including methicillin resistant S. aureus (MRSA) is continually increasing (Pediatr Dermatol 2012;29:243)
Clinical features
  • Early lesions: easily ruptured vesicopustules on an erythematous base
  • Later lesions: ruptured lesions are replaced by thick, adherent, distinct golden yellow (honey colored) crust
  • Satellite lesions due to self inoculation are common
  • Primarily a clinical diagnosis
  • Swab for culture of lesions may rarely be helpful
Prognostic factors
Case reports
  • Observation is reasonable in uncomplicated infections (Pediatr Dermatol 2012;29:243)
  • Over the counter topical agents include bacitracin and neomycin (Pediatr Dermatol 2012;29:243)
  • Topical disinfectants, including sodium hypochlorite baths, help decrease colonization (Pediatr Dermatol 2012;29:243)
  • Topical antibacterials may minimize resistance and adverse effects from systemic agents (Pediatr Dermatol 2012;29:243); include mupirocin and retapamulin
  • Oral antibacterials are indicated for infection of deeper structures including subcutaneous tissues and muscle fascia (cellulitis), fever, lymphadenopathy, pharyngitis, infections near oral cavity, scalp infections, > 5 lesions (An Bras Dermatol 2014;89:293)
Clinical images

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Crusted impetigo

Microscopic (histologic) description
  • Spongiosis of epidermis giving rise to vesicopustules in upper layers of epidermis
  • As lesions progress, epidermis may become eroded and covered with a thick layer of serous crust with neutrophilic debris and Gram positive cocci
  • Superficial dermis displays a moderately dense mixed inflammatory infiltrate
Microscopic (histologic) images

Contributed by Jerad Gardner, M.D.

Impetigo contagiosa


Impetigo contagiosa

Differential diagnosis
  • Ecthyma: may be a variant of impetigo but lesions are more punched out, sharply demarcated and result in scarring; also due to superficial bacterial infection usually with Streptococcus pyogenes
  • Secondary impetiginization: similar histologic changes to impetigo may be associated with various other skin conditions; represents secondary infection with cutaneous Gram positive cocci
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