Pyoderma gangrenosum
Pyoderma gangrenosum is a rare condition in which a deep, painful ulcer with characteristic undermined violet edges forms rapidly on the skin.
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Medicines commonly prescribed for Pyoderma gangrenosum
For informational purposes only. Always consult a doctor before using any medicine.
Dosage form: INJECTABLE, 50 mg/mlActive substance: methotrexateManufacturer: Accord Healthcare S.L.U.Prescription requiredDosage form: INJECTABLE, 27.5 mgActive substance: methotrexateManufacturer: Medac Gesellschaft Für Klinische Spezialpräparate GmbhPrescription requiredDosage form: INJECTABLE, 25 mg/mLActive substance: methotrexateManufacturer: Especialidades Farmaceuticas Centrum S.A.Prescription required
Pyoderma gangrenosum is a rare condition in which a deep, painful ulcer with characteristic undermined violet edges forms rapidly on the skin. Despite the name it is neither an infection nor gangrene: it is driven by the body's own inflammatory response. That matters not just for understanding but for treatment: antibiotics do not work, and surgical debridement can make the ulcer worse.
How it develops
- it begins as a small painful nodule, blister or pustule, often at the site of a minor injury, a needle prick or an insect bite;
- within days the lesion breaks down and the ulcer enlarges rapidly, sometimes day by day;
- the ulcer is deep, with an irregular base and undermined, overhanging edges of a bluish-violet colour;
- very severe pain — out of proportion to the size of the ulcer; this is one of the most telling signs;
- the typical site is the lower leg, but it can occur anywhere, including around a stoma after bowel surgery;
- fever, malaise and joint pains are common;
- healing leaves a characteristic thin, cribriform scar.
The key feature: any trauma to the skin, including debridement and even a biopsy, can trigger a new ulcer. This phenomenon is called pathergy, and it is why surgical cleaning is contraindicated until the inflammation is under control.
When to see a doctor
This is a condition where delay is costly: the sooner treatment starts, the smaller the scar.
- a skin ulcer is enlarging rapidly;
- the pain far exceeds what such a wound would be expected to cause;
- the ulcer edges are violet and undermined, as if overhanging;
- the wound appeared at the site of minor trauma and is not healing;
- antibiotics have had no effect — an important signal;
- there is fever and increasing malaise;
- the ulcer has appeared near a stoma;
- you have inflammatory bowel disease or a rheumatic condition and a skin ulcer has developed.
What it is associated with
In roughly half of people an associated condition is found, and looking for it is a mandatory part of the assessment:
- inflammatory bowel disease — Crohn's disease and ulcerative colitis;
- rheumatoid arthritis and other inflammatory joint diseases;
- blood disorders — myelodysplastic syndromes, leukaemias, monoclonal gammopathies;
- hepatitis;
- less commonly, a reaction to particular medicines;
- in the other half of cases there is no associated condition.
How it is diagnosed
There is no specific test — the diagnosis is made by excluding other causes of ulceration: infection, arterial and venous circulatory problems, vasculitis, malignancy, bites and the consequences of injections. A wound swab, a biopsy from the ulcer edge, blood tests, assessment of the leg circulation and, where indicated, bowel and haematological investigations are performed.
One important nuance: the biopsy here is not to find something specific but to exclude everything else. And it is taken carefully, with the risk of pathergy in mind.
Treatment
The aim is to suppress the inflammation quickly, control the pain and allow the wound to heal.
- corticosteroids — topical for small ulcers, oral or intravenous for rapidly growing ones; the mainstay of treatment;
- ciclosporin — an alternative to steroids with comparable effectiveness;
- topical calcineurin inhibitors and steroid injected into the ulcer edge;
- biologic therapy, particularly where there is inflammatory bowel disease;
- treating the associated condition — often this is what settles the picture;
- adequate pain relief — not a secondary matter here, as the pain can be severe;
- dressings that maintain a moist environment and gentle care without aggressive cleaning;
- compression if there is leg swelling, after arterial flow has been assessed;
- antibiotics only if infection is added, not to treat the ulcer itself.
Surgical debridement and skin grafting are only possible once treatment has brought the inflammation under control; before that, the wound would enlarge.
What you can do
- protect the skin from any trauma, including scratches and tight footwear;
- do not try to clean the wound yourself and do not use harsh antiseptics;
- elevate your legs when sitting;
- do not smoke;
- eat adequately with enough protein — without it the wound will not heal;
- do not put up with pain: tell your doctor if the pain relief is not working;
- take prescribed medicines regularly and do not stop them at the first sign of improvement.
Outlook
With the right treatment the ulcers heal, but it takes weeks or months. Characteristic scars remain. The condition can recur, including at a new site after trauma, so continued follow-up and control of any associated disease matter.
Common questions
Is it an infection? No. That is why antibiotics do not help, even though they are often the first thing prescribed.
Is it gangrene? No, despite the name. The circulation is intact and the mechanism is inflammatory.
Why can't the wound be cleaned surgically? Because of pathergy: trauma makes the ulcer grow. It becomes possible only after the inflammation is suppressed.
Is it contagious? No.
Online consultation
In an online consultation the doctor reviews photographs of the ulcer and its edges, notes the mismatch between the pain and the size of the wound, works out why antibiotics did not help, plans the investigations needed to exclude other causes, and explains why the wound should not be cleaned before treatment begins.
This material is for information only and does not replace a medical consultation.
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Reviewed on Jul 30, 2026
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