Pyoderma gangrenosum

Symptoms of pyoderma gangrenosum

Pyoderma gangrenosum usually appears suddenly as either a small pimple, red bump or blood blister.

The skin then breaks down into a painful ulcer with a purple or blue edge that may ooze fluid. The ulcer can grow quickly and several may develop in the area.

If the ulcer gets infected, you may also feel unwell and develop a high temperature (fever).

Pyoderma gangrenosum usually occurs on the legs, although it can affect any area of skin. It sometimes develops around an injury or surgical wound.

Pyoderma gangrenosum is not related to gangrene.

When to get medical advice

See your GP as soon as possible if you think you have pyoderma gangrenosum.

It's a serious condition that can progress quickly. So it's important to get it diagnosed and treated as soon as possible.

Early treatment can also help reduce the risk of scarring.

If you have one of the conditions listed below, you could also contact your care team instead of your GP.

Causes of pyoderma gangrenosum

The exact cause of pyoderma gangrenosum is not understood. But it's thought to be a reaction to a disease or illness.

Many people have no related condition and there's no obvious reason for it.

The skin reaction isn't passed down to children from their parents through genes.

It's also not contagious, so can't be transferred from or to another person.

The reaction may sometimes be triggered by minor skin damage or an injury, for example, it may develop around a wound, a needle prick, a biopsy or an insect bite.

When the affected skin tissue is tested, it usually has a high concentration of neutrophils (white blood cells involved in inflammation).

This means pyoderma gangrenosum may be related to overactivity of the immune system.

People at risk of pyoderma gangrenosum

People with the following health conditions are most likely to develop pyoderma gangrenosum, even if the condition is mild or well controlled:

• inflammatory bowel disease – including:
  • ulcerative colitis
  • Crohn's disease
• rheumatoid arthritis – a long-term condition causing pain, swelling and stiffness in the joints
• blood dyscrasias – blood disorders including: 
  • polycythaemia
  • leukaemia
  • myeloma
  • lymphoma
• hepatitis – inflammation of the liver
• granulomatosis with polyangiitis – a rare condition in which the walls of blood vessels become inflamed
• PAPA syndrome – a rare genetic disorder

Diagnosing pyoderma gangrenosum

There's no specific blood test for pyoderma gangrenosum.

If your doctor thinks you might have the condition, they may ask for some tests, including:

• taking a small sample of your skin (biopsy) to help rule out other causes of skin ulcers
• taking a swab of the wound to check for any infection
• blood tests to check for conditions associated with pyoderma gangrenosum

Treating pyoderma gangrenosum

Pyoderma gangrenosum often heals with simple treatments.

It may take some time and often leaves some scarring in the affected area.

Some people heal very slowly, over months or years. Others may find the condition clears up within a few weeks. In some cases, it returns after treatment.

There are a number of treatment options, but there's no clear evidence to suggest which the best one is.

If you have the condition, the doctor treating you will discuss with you the most appropriate treatment options. These may include:

• creams, ointments or injections
• steroid tablets
• immunosuppressants - medications that reduce the activity of the immune system

Care of the wound

Regular dressings may need to be applied to soak up any discharge and help retain the creams applied to the wound. 

Any severely damaged tissue should be gently removed by a doctor or nurse.

More useful links

• How to use your health services