by Scholten A


Pyoderma gangrenosum is a rare form of open sores (ulcers) on the skin. The sores often occur on the lower legs. However, they can happen anywhere on the skin.

Side View of Skin Ulcer
Skin Ulcer small
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The exact cause of pyoderma gangrenosum is not known. It may be caused by the immune system attacking an area of the skin.

Risk Factors

This problem is more common in women and people between 20 and 60 years old. The risk is higher in those who have:


The main symptom of pyoderma gangrenosum is a painful skin sore. Sores may begin as small bumps from an injury. However, a sore can grow up to 7.9 in (inches) (20 cm [centimeters]). The sores often have purple edges that look worn.


The doctor will ask about your symptoms and health history. A physical exam will be done. You may be sent to a skin doctor. Pyoderma gangrenosum may be diagnosed by how it looks.

The doctor may want to rule out other causes of the skin sores. Tests may be done, such as:

  • Sample of fluids from the sores—to look for infection or causes of infection
  • Biopsy—a tissue sample to be tested
  • Blood tests


The goal is to help sores heal and prevent further problems. Underlying conditions may also need to be treated. Options may be:

  • Medicines to help heal sores, such as:
    • Corticosteroid pills—to reduce inflammation
    • Steroid cream or an injection—for smaller sores
  • Immunosuppressants—to stop the immune system from attacking the skin

Other medicines may be given to treat underlying conditions.

Surgical skin grafts may be done—if other treatments do not work.


There are no current guidelines to prevent pyoderma gangrenosum.


American Academy of Dermatology 

American Autoimmune Related Diseases Association 


Canadian Dermatology Association 

Canadian Institute for Health Information 


Alavi A, French LE, et al. Pyoderma gangrenosum: an update on pathophysiology, diagnosis and treatment. Am J Clin Dermatol. 2017;18(3):355-372.

Pyoderma gangrenosum. DermNet New Zealand website. Available at: Accessed March 2, 2021.

Pyoderma gangrenosum. EBSCO DynaMed website. Available at: . Accessed March 2, 2021.

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