Unifying Concepts

Diagnostic Criteria of Ulcerative Pyoderma Gangrenosum (PG)

Pyoderma gangrenosum (PG) is a reactive non-infectious inflammatory dermatosis falling under the spectrum of the neutrophilic dermatoses, which includes Sweet’s syndrome and Behcet’s syndrome.

Diagnostic tool for pyoderma gangrenosum

Major criteria

  • Rapid progression of a painful necrolytic cutaneous ulcer with an irregular, violaceous and undermined border
  • Other causes of cutaneous ulceration excluded

Minor criteria

  • History of pathergy or cribriform scarring clinically
  • Associated systemic disease (inflammatory bowel disease, arthritis, IgA gammopathy or underlying malignancy)
  • Classic histopathological findings
  • Treatment response (rapid response to systemic steroid treatment – 50% improvement in 1 month)

The diagnostic tool requiring two major and two minor criteria, maintaining PG as a diagnosis of exclusion.

Improved diagnostic tool for pyoderma gangrenosum

Major criterion

  • Biopsy of ulcer edge demonstrating neutrophilic infiltrate

Minor criteria

  • Exclusion of infection
  • Pathergy
  • History of inflammatory bowel disease or inflammatory arthritis
  • History of papule, pustule or vesicle ulcerating within 4 days of appearing
  • Peripheral erythema, undermining border, and tenderness at ulceration site
  • Multiple ulcerations, at least one on anterior lower leg
  • Cribriform or ‘wrinkled paper’ scar(s) at healed ulcer sites
  • Decreased ulcer size within 1 month of initiating immunosuppressive medication(s)

These new criteria are based on a consensus of international experts, which require a larger and four minor criteria.



  1. Maverakis E, Ma C, Shinkai K, Fiorentino D, Callen JP, Wollina U, Marzano AV, Wallach D, Kim K, Schadt C, Ormerod A, Fung MA, Steel A, Patel F, Qin R, Craig F, Williams HC, Powell F, Merleev A, Cheng MY. Diagnostic Criteria of Ulcerative Pyoderma Gangrenosum: A Delphi Consensus of International Experts. JAMA Dermatol. 2018 Apr 1;154(4):461-466. [Medline]
  2. George C, Deroide F, Rustin M. Pyoderma gangrenosum – a guide to diagnosis and management. Clin Med (Lond). 2019 May;19(3):224-228. [Medline]


Created Oct 15, 2019.

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