Definition

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 Copyright © Nucleus Medical Media, Inc.

Causes

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:

• Ulcerative colitis
• Crohn disease
• Chronic active hepatitis
• Rheumatoid arthritis
• Polycythemia vera
• Myeloma
• Behcet syndrome
• Acute myelogenous leukemia
• Chronic myelogenous leukemia

Symptoms

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.

Diagnosis

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 tissue sample examined under a microscope
• Blood tests

Treatment

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

Prevention

There are no current guidelines to prevent pyoderma gangrenosum.