What is pyoderma gangrenosum?
Pyoderma gangrenosum is a rare treatable cause of skin ulceration. Pyoderma gangrenosum belongs to a group of related conditions called neutrophilic dermatoses. Although it sounds similar to gangrene, it is not a type of gangrene. Pyoderma gangrenosum is not contagious and cannot be transferred from person to person.
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What causes pyoderma gangrenosum?
Approximately 50% of people with pyoderma gangrenosum have no known cause for it. In some cases it may start after trauma to the skin. Other cases are associated with an underlying medical condition such as inflammatory bowel disease, arthritis or certain blood disorders. It is important to know that having pyoderma gangrenosum does not mean that you have these diseases but your specialist or doctor will consider and exclude them.
What does pyoderma gangrenosum look like?
Pyoderma gangrenosum usually occurs in young to middle-aged adults. The appearance of the condition may vary. It may start as a small pimple, red bump, pustule or blood-blister. The skin usually breaks down to form an ulcer which often oozes fluid. The ulcer can enlarge rapidly. The edge of the ulcer may look purplish. Once the ulcer has healed, the resulting scar may be darker than the surrounding skin (hyperpigmented), pale, thin and wrinkled in appearance or pitted.
The most common place for pyoderma gangrenosum to occur is on the legs, but it may occur on any part of the skin. Sometimes it may occur around the site of a stoma (e.g. colostomy), or in a surgical wound.
What are the symptoms of pyoderma gangrenosum?
There is usually a single large ulcer. Occasionally there may be multiple ulcers. Ulcers may become infected, oozing fluid or pus. Pain or discomfort from the ulcer is common. Pyoderma gangrenosum is not a skin cancer and does not lead to cancer.
How is pyoderma gangrenosum diagnosed?
No specific test exists to confirm a diagnosis of pyoderma gangrenosum. Diagnosis is based on a combination of clinical assessment, exclusion of other causes of skin ulceration and certain investigations .
Your doctor will need to exclude other conditions that can look like pyoderma gangrenosum such as venous ulcers, inflammation of blood vessels or skin, infection, injury and cancer. The wound may be swabbed to rule out an infection. You may also be offered blood, urine and stool tests to exclude certain conditions that can be associated with pyoderma gangrenosum.
Your doctor may consider taking a small sample of skin (biopsy) to be examined under the microscope in a laboratory. This test is helpful in ruling out other causes of skin ulceration. Pyoderma gangrenosum does not have a specific appearance under the microscope however there is usually an abundance of white blood cells (neutrophils).
Pyoderma gangrenosum is not hereditary and is not passed from parents to their children.
How can pyoderma gangrenosum be treated?
Pyoderma gangrenosum is often difficult to treat and may take some time to heal. More than one treatment may need to be tried. Skin grafts and surgery are not treatment options as they often fail and may cause enlargement of the ulcer.
Treatment depends on the severity of the disease. Mild disease is treated with topical creams or ointments, including corticosteroids and calcineurin inbhibitors (such as tacrolimus). More severe disease is often managed with oral or injection therapies.
- Antibiotics such as dapsone or minocycline
- Steroid tablets (e.g. prednisolone). These work by reducing inflammation. They may be used alone or in combination with other agents.
- Immunosuppressive medicines such as Mycophenolate mofetil, Ciclosporin or Azathioprine. These work by reducing your body’s natural immune response which is involved with pyoderma gangrenosum.
- Targetted therapies such as infliximab are used in pateints with pyoderma gangrenosum which is resistant to treatment. These work by blocking specific parts of the immune system.
In very severe cases your doctor may consider other stronger, immunosuppressive medicines including cyclophosphamide, intravenous steroids or immunoglobulins.