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Definition | Causes | Risk Factors | Symptoms | Diagnosis | Treatment | Prevention


A skin ulcer is an open sore in the skin. Pyoderma gangrenosum is an uncommon form of skin ulcers. It usually occurs on the lower legs, but can occur anywhere on the skin.

Side View of Skin Ulcer

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Pyoderma gangrenosum is thought to be caused by a problem with the immune system. The immune system finds and attacks foreign items in the body like viruses. Sometimes the immune system attacks the body's own tissue. In this case, the immune system attacks an area of the skin.

Risk Factors

Pyoderma gangrenosum is more likely to occur in people who have other underlying medical conditions, such as:


The main symptom of pyoderma gangrenosum is a painful skin ulcer. These ulcers may begin as small-irritated bumps from an injury. However, the ulcer can grow up to 7.9 in (inches) (20 cm [centimeters]). The ulcers often have purple edges that appear worn away.


Your doctor will ask about your symptoms and medical history. A physical exam will be done. You may be referred to a skin specialist. Pyoderma gangrenosum is diagnosed by its appearance. Your doctor will also want to rule out other conditions that can cause skin ulcers.

To look for other factors that could cause ulcers, your doctor may order:

  • Sample of ulcer fluids—to look for infection or items that can cause infection
  • Biopsy—a sample of tissue
  • Blood tests


Talk with your doctor about the best treatment plan for you. Treatment options include:

Oral steroid medications and cyclosporine are the first line of treatment for most. These medications are used to help calm the body's immune system. This should stop or slow the attack on the skin.

Smaller ulcers may be treated with a topical steroid cream or an injection.

There are a variety of medications that can help calm the immune system. Your doctor may choose other medications based on other medical conditions you may have. You may also be able to better tolerate some medications over others.

Talk to your doctor about which medications may work best for you.

Ulcers often begin at the site of injuries. Take precaution to prevent injuries when possible. Wear proper safety gear and avoid high impact or full contact activities.

See your doctor as soon as you notice a possible ulcer.


There is no known way to prevent pyoderma gangrenosum.


American Academy of Dermatology


American Autoimmune Related Diseases Association



Canadian Dermatology Association


Canadian Institute for Health Information



Charles CA, Leon A, et al. Etanercept for the treatment of refractory pyoderma gangrenosum: a brief series. Int J Dermatol. 2007 Oct;46(10):1095-9.

Pyoderma gangrenosum. DermNet NZ website. Available at: http://www.dermnetnz.org/reactions/pyoderma-gangrenosum.html. Accessed December 7, 2012.

Pyoderma gangrenosum. EBSCO DynaMed website. Available at: https://dynamed.ebscohost.com/about/about-us. Updated January 14, 2012. Accessed December 7, 2012.

Reguiaï Z, Grange F. The role of anti-tumor necrosis factor-alpha therapy in Pyoderma gangrenosum associated with inflammatory bowel disease. Am J Clin Dermatol. 2007;8(2):67-77. Review.

Last reviewed December 2012 by Michael Woods, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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