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Pustular skin conditions

Author: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, September 2015. DermNet NZ Revision September 2021

Pustular skin conditions — codes and concepts

What are pustules?

Pustules are smaller than 5–10 mm, and filled with pus, that is, purulent material composed of inflammatory cells (neutrophils).

  • Pus can indicate bacterial, fungal or viral infection
  • Some pustules are sterile and are due to inflammatory skin disease

This topic provides a differential diagnosis of pustular skin conditions.

Acute mainly pustular generalised eruptions

Generalised pustular psoriasis

  • Febrile illness
  • Annular plaques studded with pustules

Generalised pustular psoriasis

Acute generalised exanthematous pustulosis

  • Febrile illness
  • Drug eruption
  • Diffuse superficial pustules

Acute generalised exanthematous pustulosis (AGEP)

Acute mainly pustular localised eruptions


  • Rapidly enlarging plaque
  • Swab Staphylococcus aureus +/- Streptococcus pyogenes



  • Based on hair follicle
  • May lead to abscess formation
  • Swab Staphylococcus aureus



  • Itchy or painful follicular pustules
  • Various types

Bacterial folliculitis

Dermatophyte infection

  • Kerion: abscess formation
  • Due to zoophilic fungus, eg Microsporum canis



Candidal intertrigo


  • Sweat rash


Chronic mainly pustular eruptions


  • Face, neck, upper trunk
  • Comedones + inflammatory lesions

Acne vulgaris

Acneform eruptions

Acneform eruptions


  • Irregular pustules on hands and feet
  • Burrows between fingers, volar wrists
  • Papules axillae, groin
  • Generalised itchy rash


Dermatophyte infection

  • Irregular annular plaque with peripheral scale
  • Pustules on feet due to Trichophyton interdigitale

Dermatophyte infections

Palmoplantar pustulosis

  • Hands, feet
  • Sterile tender, itchy, pustules

Palmoplantar pustulosis

Erosive pustular dermatosis

  • Sun damaged scalp
  • May develop squamous cell carcinoma
  • Lakes of greenish pus
  • Culture may reveal Staphylococcus aureus

Many skin conditions present with pustules - see links to more On DermNet NZ in the Related Information Section below.



  • Bachelez H. Pustular psoriasis and related pustular skin diseases. Br J Dermatol. 2018;178(3):614-18. doi:10.1111/bjd.16232 PubMed 
  • Filosa A, Filosa G. Neutrophilic dermatoses: a broad spectrum of disease. G Ital Dermatol Venereol. 2018;153(2):265-72. doi:10.23736/S0392-0488.18.05841-8 Journal 
  • Kutlubay Z, Tanakol A, Engýn B, et al. Newborn Skin: Common Skin Problems. Maedica (Bucur). 2017;12(1):42-7. PubMed Central 
  • Mengesha YM, Bennett ML. Pustular skin disorders: diagnosis and treatment. Am J Clin Dermatol. 2002;3(6):389-400. doi:10.2165/00128071-200203060-00003 PubMed 

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