Pyoderma gangrenosum

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Clinical Features

Pyoderma gangrenosum on the leg of a person with ulcerative colitis.
Pyoderma gangrenosum of upper back.
  • Extracutaneous manifestations (due to sterile neutrophilic infiltrates):
    • Culture-negative pulmonary infiltrates most common
    • cardiovascular, CNS, GI, eyes, liver, spleen, bones, lymph nodes
  • Initial lesion: bite-like, small, red papule or pustule (many patients attribute spider bite)
  • Changes into larger, ulcerative lesion
  • Two primary variants:
    • Classic ulcerative form - usually on legs, deep ulceration, violaceous border along ulcer bed
    • Superficial, atypical form - hands/forearms/face, vesiculopustular
    • Less common variants: 1) Peristomal pyoderma, 2) Genital pyoderma (must differentiate from STI), 3) Pyostomatitis vegetans (intraoral)

Differential Diagnosis

  • Systemic diseases
    • Neutrophilic dermatoses (Sweet, Behcet's disease, etc.)
    • Calciphylaxis - very important to differentiate due to treatment
    • Arterial/venous insufficiency
    • Blastomycosis
    • Hidradenitis suppurative
    • TB gumma, mycobacterial infections
    • Malignancy (squamous cell)
    • Vasculitis
    • Ecthyma gangrenosum (pseudomonas)


  • Diagnosis of exclusion
  • No specific criteria
  • CBC, CMP, UA, hepatitis profile, coags, VDRL
  • Autoimmune labs: ANCA, antiphospholipid antibody
  • Tissue cultures (comprehensive, all organisms)
    • Coags
    • Anti-phospholipid antibody
    • Referral for heme malignancy workup
    • Referral for IBD workup
  • CXR if systemic disease suspected


  • Nonsurgical management
    • Necrotic tissue should be gently removed
    • Wide surgical debridement results in enlargement of ulcer
  • Medical management


  • Usually discharge with derm and/or surgery follow-up and referral for IBD and malignancy workup

See Also

External Links