Pyoderma Gangrenosum – a rare cause of leg ulceration

In rare cases, some leg ulcers are caused by a condition called Pyoderma Gangrenosum, often known as PG. It is very important that you recognise a wound that does not have the standard features of venous ulceration – early diagnosis means that swift treatment can follow.

A diagnosis of Pyoderma Gangrenosum can be quite scary for the patient. Like all conditions, having a diagnosis is the first step to getting the correct treatment so that the wound heals.

What is Pyoderma Gangrenosum?

Pyoderma Gangrenosum is a rare but treatable cause of skin ulceration, autoinflammatory disorder causing neutrophils to infiltrate the skin; a biopsy at the ulcer edge would hopefully demonstrate this but can be absent in active treatment or where there has been a delay in diagnosis. It can happen anywhere on the body – PG can start spontaneously or start following a surgical procedure. PG lesions or wounds on the leg can be slow to heal because wounds on the legs heal more slowly that other parts of the body.

Despite its name, it is not a type of gangrene. Pyoderma Gangrenosum is not contagious and cannot be passed from person to person.

What does Pyoderma Gangrenosum looks like? And image of Pyoderma Gangrenosum on a leg
Pyoderma gangrenosum can cause large, painful sores (ulcers) to develop and can be confused with Venous ulcers. Correct diagnosis is essential.

What causes Pyoderma Gangrenosum?

The cause of Pyoderma Gangrenosum is often not known. Approximately half the people diagnosed have no known cause for it. It may start after trauma to the skin. Pyoderma Gangrenosum can sometimes be associated with an underlying medical condition such as inflammatory bowel disease, arthritis or certain blood disorders.

What are the symptoms of Pyoderma Gangrenosum?

The condition usually starts with one single ulcer – this can unfortunately deteriorate quite quickly to a large or deep wound. Occasionally there may be multiple ulcers. Pain or discomfort from the ulcer is common, and the edge of the ulcer initially may look purplish. Sometimes the person may remember that it started like a red nodule or blood blister – sometimes people think they had a nasty insect bite. Pyoderma Gangrenosum is not a skin cancer and does not lead to cancer.

Diagnosing Pyoderma Gangrenosum

There is no specific blood test for Pyoderma Gangrenosum.

Where a wound is not responding to standard therapies and is continuing to deteriorate, seek urgent specialist help from Dermatology.

They will require:

  • Taking a biopsy from the edge of the ulcer; this will be reviewed for the presence of neutrophils or 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

PG can be difficult to diagnose because it does not always show the classic signs of the disease, it may be confused with other conditions and even the biopsy can be ambiguous. Thus a diagnosis of PG can be given because the consultant now knows what ‘it is not’. In these circumstances it is a ‘diagnosis of exclusion’ – the working diagnosis of Pyoderma Gangrenosum allows a medical diagnosis and treatment to follow.

Treatment of Pyoderma Gangrenosum?

Pyoderma Gangrenosum is often difficult to treat and may take some time to heal. Treatment requires the following important interventions.

Medical management by a dermatologist

The consultant aims to get the inflammatory condition under control. Oral medication may include steroids, special antibiotics OR immunosuppressive medication. A topical steroid ointment may be applied directly to the wound. More than one treatment may need to be tried; this will be based on the patient’s experience of the medication and whether the wound shows a positive response to the chosen medication.

The patient will need regular medical review and regular blood tests to ensure the medication is not causing additional problems.

Management of pain

Management of pain is essential – this condition can be extremely painful and the patient will need strong analgesia initially. Please assess for and manage neuropathic pain. Anti-neuropathic medication will be required if compression is to be tolerated. Pain will reduce if the inflammatory condition is being controlled.

Compression therapy (may include bandages or wraps)

Compression is an essential part of the treatment if you have PG on your legs or feet and can get forgotten. Medical management may not be enough on its own to control this condition. Even if the leg is not very swollen the compression bandage or sock will reduce the level of exudate. You may want to start with mild compression, but increase the level of compression as soon as you can so the patient can benefit from the anti-inflammatory properties of the compression therapy.


We would like to acknowledge the British Association of Dermatologists for providing helpful information.

Further reading

British Association of Dermatologists (Website)

DermNet NZ (Website)

Dowload a patient information leaflet as a pdf to print

Other support

Accelerate We have a clear vision at Accelerate – Our vision is to boldly transform chronic wound and lymphoedema care. And we do this by developing and increasing access to world-class treatments and thinking in chronic wound and lymphoedema care. We're based in East London but can accept national referrals from your GP / specialist to our world-class centre where we pioneer and trial experimental new treatments for chronic wounds, lymphoedema and mobility challenges.

Contact details
020 3819 6022
Find out more on the Accelerate website

The Lindsay Leg Club Foundation Promoting and supporting community based treatment, health promotion, education and ongoing care for people who are experiencing leg-related problems - including leg ulcers and other wound care issues.

Contact details
01473 749565
Find out more on the Lindsay Leg Club Foundation website

NHS Choices the official NHS website, which provides vital information and support about leg and foot signs and other symptoms.

Contact details
Call 111 - for non-emergency medical advice
Find out more on the NHS Choices website

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