SynopsisCodesLook ForDiagnostic PearlsDifferential Diagnosis & PitfallsBest TestsManagement PearlsTherapyDrug Reaction DataReferences

View all Images (5)

Pyoderma gangrenosum - Anogenital in
See also in: Overview,Cellulitis DDx
Other Resources UpToDate PubMed

Pyoderma gangrenosum - Anogenital in

See also in: Overview,Cellulitis DDx
Contributors: Erin X. Wei MD, Jeffrey M. Cohen MD, Vivian Wong MD, PhD, Susan Burgin MD
Other Resources UpToDate PubMed


Pyoderma gangrenosum (PG) is an inflammatory, noninfectious, ulcerative, neutrophilic skin disease of uncertain etiology commonly misdiagnosed as an aggressive skin infection. PG occurs most often in middle-aged adults, but it can affect individuals of any age. There is no predilection for sex or any race or ethnicity.

PG can take on a number of differing clinical presentations. The 2 most common presentations are a classic ulcerative form, which often involves the lower extremities, and a vesiculobullous form, which is more superficial and tends to occur on the upper extremities, including the hands. This subtype is most commonly seen in patients with an associated lymphoproliferative disorder. Other variants include pustular, vegetative, and peristomal PG. Fever, toxicity, and pain can be associated with the onset of PG. Rarely, PG can involve the eyes. Extracutaneous manifestations may take the form of sterile neutrophilic abscesses, such as in the lungs, heart, gastrointestinal (GI) tract, liver, eyes, central nervous system (CNS), and lymphatic tissue.

Necrotizing neutrophilic dermatosis describes a subset of patients with severe acute febrile neutrophilic dermatosis (Sweet syndrome) or PG who, in addition to their cutaneous disease, develop fever, leukocytosis (or a leukemoid reaction), and features of shock. Skin pain is a prominent symptom. Additionally, soft tissues underlying areas of skin involvement may be affected with neutrophilic infiltrates and necrosis.

Although the exact cause of PG is unknown, neutrophil dysfunction, inflammation, and genetics are all thought to play a role. Additionally, PG has associations with a number of systemic illnesses. In about 50% of cases, there is an association with a systemic disease, such as ulcerative colitis, Crohn disease, arthritis, myeloma, leukemia, monoclonal gammopathy, granulomatosis with polyangiitis, collagen vascular disease, metabolic syndrome, or Behçet disease, among other disorders, including genetic conditions. Surgery by itself can be a precipitating cause (postoperative PG). Levamisole-contaminated cocaine has been associated with PG lesions ranging from vesiculopustules to bullae to larger ulcers; most patients demonstrated positivity for antiphospholipid or anticardiolipin antibodies. PG can be associated with autoinflammatory syndromes (eg, PAPA syndrome [pyogenic arthritis, PG, and acne]; SAPHO syndrome [synovitis, acne, pustulosis, hyperostosis, and osteitis]; and PAPASH syndrome (pyogenic arthritis, PG, acne, and hidradenitis]).

PG can have either an acute or chronic course and results in extensive scarring (which can be cribriform or keloidal with dyspigmentation, especially in patients with darker skin colors). Surgical intervention is a common exacerbating factor because PG demonstrates pathergy, a phenomenon by which skin trauma can lead to worsening disease.


L88 – Pyoderma gangrenosum

74578003 – Pyoderma gangrenosum

Look For

Subscription Required

Diagnostic Pearls

Subscription Required

Differential Diagnosis & Pitfalls

  • Infectious causes of ulcers can mimic PG. PG is in the family of neutrophilic skin disorders, which includes Acute febrile neutrophilic dermatosis, Subcorneal pustular dermatosis, and Behçet syndrome. As many infectious processes can cause a similar picture (eg, Progressive bacterial synergistic gangrene, Blastomycosis, other deep fungal infections, Cutaneous amebiasis, Sporotrichosis, Atypical mycobacterial infection), PG is a diagnosis of exclusion.
  • Calciphylaxis – can present as a painful ulcer on the penis
  • Primary syphilis
  • Chancroid – usually present around genital skin
  • Genital herpes simplex virus (HSV) – usually grouped, punched-out erosions
  • Ecthyma
  • Ecthyma gangrenosum
  • Factitial ulcer – sharp geometric borders
  • Cutaneous squamous cell carcinoma
  • Traumatic ulceration
  • Tertiary syphilis
Pustules / nodules:
  • Cellulitis
  • Folliculitis
  • Furunculosis
  • Arthropod bite or sting or Spider bite
  • Bullous impetigo
  • Panniculitis
  • Acute febrile neutrophilic dermatosis
  • Bromoderma
  • Pyodermatitis vegetans
The differential diagnosis for an immunocompromised patient also includes:
  • Chronic Genital herpes simplex virus
  • Ulcerative Kaposi sarcoma (AIDS-associated Kaposi sarcoma and Non-AIDS Kaposi sarcoma)

Best Tests

Subscription Required

Management Pearls

Subscription Required


Subscription Required

Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

Subscription Required


Subscription Required

Last Reviewed:10/22/2023
Last Updated:11/26/2023
Copyright © 2024 VisualDx®. All rights reserved.
Pyoderma gangrenosum - Anogenital in
See also in: Overview,Cellulitis DDx
A medical illustration showing key findings of Pyoderma gangrenosum (Classic Ulcerative Form)
Clinical image of Pyoderma gangrenosum - imageId=798076. Click to open in gallery.  caption: 'A close-up of a large ulcer with surrounding re-epithelialization.'
A close-up of a large ulcer with surrounding re-epithelialization.
Copyright © 2024 VisualDx®. All rights reserved.