Pyoderma gangraenosum

Last Updated: 2023-07-07

Author(s): Anzengruber F., Navarini A.

ICD11: EB21

Brocq, 1916; Brunsting u. Goeckermann, 1930

PG, ulcerative dermatitis, Meleney ulcer, pyodermia vegetans et ulcerans gangraenosa

  • Rare, sometimes painful and destructive, sterile, inflammatory dermatosis associated with abscesses and necrosis
  • It is chronically progressive and resistant to common ulcer therapy

  • Rare condition
  • Slight female predilection
  • Mostly between the ages of 25 and 54
  • Smoking can increase the risk for PG

  • Ulcerative form (classic and most common type): rapidly deep- or area-progressive, purulent-serous ulceration with undermined, livid-red margins. Associated arthritides, inflammatory bowel disease, monoclonal gammopathies  
  • Pustular form: 0.2-0.8 cm pustules, often associated with larger inflammatory plaque(s). Commonly associated inflammatory bowel disease
  • Bullous form: Subepidermal blistering with inflammatory rim that erodes or ulcerates. 
  • Vegetative superficial granulomatous form: superficial mostly solitary ulcer without undermined rim, often in surgical scars.
  • Peristomal form: Ulcerating, painful  papules or plaques around stomas. Further development into the typical ulcerative form with undermined margins.
  • Mucosal type = pyostomatitis vegetans: this very rare, chronic ulcerative clinical picture of the  oral mucosa is considered by some authors to be a (mucosal) variant of pyoderma gangraenosum.


  • Exact genesis unclear, discussed are abnormal function of neutrophil granulocytes, dysregulation of the immune system, genetic predisposition
  • Frequent association (> 50%) with systemic diseases: e.g. chronic inflammatory bowel diseases, rheumatoid arthritis, haematological diseases or malignancies


  • Very painful focal skin lesions, often initially consisting of blisters, papules and pustules
  • Pathergy: Often develops after minor trauma (insect bites, small injuries)
  • During progression, deep ulcers develop across the dermis with central necrosis
  • Continuous progression, centrifugal spread
  • Typical: Wall-like, undermined, very painful deep red marginal zone
  • Smudgy, spongy consistency.

  • There are no universal diagnostic criteria, however in JAMA Derm 2018 Maverakis et al published a Delphi consensus (cited verbatim): 
    • Major criterion: Biopsy of ulcer edge demonstrating neutrophils
    • Minor critera (4 of 8): no infection; pathergy; IBD/Arthritis; papule/pustule/vesicle ulcerating within 4 days after appearance; peripheral erythema, undermined border, tenderness at ulceration site; multiple ulcerations including 1 on anterior lower leg; cribriform or wrinkles scar at healed sites; ulcer decreases size after 1 month of immunosuppressives. 
  • History of present illness
  • Clinical features
  • Lab:
    • mildly elevated inflammatory parameters
    • mild anaemia
    • negative ANAs, cANCAs 

Predilection sites: Extensor sides of the lower extremities, even though these are also the site of most other differentials! 

  • Nonspecific histology
  • Dermal abscesses of polymorphonuclear neutrophils
  • Later transition to a mixed cell infiltrate including plasma cells, accompanied by oedema of the papillary dermis, necrosis


Needless debridement by surgeons when diagnosis is delayed.

Not possible before diagnosis, after diagnosis immunosuppressives should be used until the tendency to form larger ulcers has ceased. 

  • Chronic, progressive course
  • Frequent recurrences
  • Spontaneous healing rather rare

  1. Powell FC, Hackett BC. Pyoderma Gangrenosum. In: Wolff K, Goldsmith LA, Katz SL, Gilchrist BA, Paller AS, Leffell DJ, editors. Fitzpatrick's Dermatology in General Medicine. 7th ed. Vol. 1. New York: McGraw Hill; 2007. pp. 296–302.
  2. Powell FC, Schroeter AL, Perry HO, Su WP. Direct immunofluorescence in pyoderma gangrenosum. Br J Dermatol. 1983;108:287–93
  3. Hughes AP, Jackson JM, Callen JP. Clinical features and treatment of peristomal pyoderma gangrenosum. J Am Med Assoc. 2000;484:1546–8.
  4. Von den Driesch P. Pyoderma gangrenosum: A report of 44 cases with follow- up. Br J Dermatol. 1997;137:1000–5
  5. Jacob SE, Weisman RS, Kerdel FA. Pyoderma gangrenosum: Rebel without cure. Int J Dermatol. 2008;47:192–4.
  6. Gameiro A, Pereira N, Cardoso JC, et al. Pyoderma gangrenosum: challenges and solutions. Clin Cosmet Investig Dermatol 2015;8:285–93.
  7. Holland SM. Chronic granulomatous disease. Clin Rev Allergy Immunol 2010;38:3–10.
  8. Bellak JM, Bell MC, Durrani SR, et al. Classical pyoderma gangrenosum associated with abnormal neutrophil oxidative burst. J Allergy Clin Immunol 2012;129:AB159.doi:10.1016/j.jaci.2011.12.358.