A Burn Scar or Leg Ulcer That Never Heals: When a Biopsy Is Needed to Rule Out Skin Cancer
Written by Dr. Ashutosh A Shah, M.B.B.S., M.S., M.Ch., D.N.B., Board Certified Plastic Surgeon. Reg. no. G-26257. 22+ years in plastic and reconstructive surgery.
Medically reviewed by Dr. Ashutosh A Shah · Published [YYYY-MM-DD] · Last reviewed 24 October 2026
A leg ulcer or sore in an old burn scar that has not healed after about three months of correct treatment should have a biopsy. Raised rolled edges, bleeding on touch, an ulcer that keeps growing or a new lump in a scar can signal Marjolin's ulcer, a skin cancer that needs excision and reconstruction.
Most ulcers that refuse to close have an ordinary cause, such as poor circulation, vein disease, pressure or infection. Those causes, the tests that find them and the common myths are covered in Why leg ulcers stay open. This page answers one narrower question: when to biopsy a non healing ulcer, and what happens if the result shows cancer.
When should a non-healing leg ulcer be biopsied?
When it has not improved after about 12 weeks of correct treatment, or when it looks unusual at any stage. The Scottish guideline on chronic venous leg ulcers, SIGN 120, recommends that patients with a non-healing or atypical leg ulcer are referred for consideration of biopsy, and names failure to progress after 12 weeks of active treatment as the trigger. The NHS leg ulcer guide notes that most venous ulcers heal within 6 months with proper care, so one that is still open well beyond that needs a closer look.
Why can a long-standing wound turn cancerous? When to see an old burn scar ulcer doctor in Morbi
Because skin that breaks down and repairs itself again and again, for years, can eventually start to grow abnormally. Scar tissue also has fewer blood vessels and a weaker local immune defence, so an early cancer can grow in it unnoticed.
- Marjolin's ulcer defined: a skin cancer, most often squamous cell carcinoma, that develops in an old scar or a chronic wound.
- Burn scars are the classic site. DermNet estimates that about 2% of thermal burn scars become Marjolin's ulcers.
- It appears late. The average gap between the original injury and the cancer is about 30 years, with a reported range of 10 to 75 years.
- The legs and feet are the commonest sites, and men are diagnosed two to three times as often as women.
- Other chronic wounds can carry it too, including long-standing bone infection, and rarely venous ulcers and pressure sores.
Can an old burn scar turn into cancer?
Yes, although it is uncommon. A burn from childhood that healed decades ago can develop a sore that will not close, or a new lump, later in life. That change, not the scar itself, is the warning sign.
Which signs in an ulcer or scar should prompt a biopsy?
Any change in an old scar, and any ulcer that does not behave like an ordinary healing wound. A healing ulcer gets smaller, its base turns pink and grainy, and its edges slope gently inward. A cancer behaves differently.
Red-flag checklist for ulcers and scars:
- Open for more than three months despite correct treatment
- Edges that are raised, rolled, hard or turned outward
- A base that bleeds easily when touched or dressed
- Steady growth in size, even while being treated
- A new lump, nodule or cauliflower-like growth in a scar or ulcer
- A sore in an old burn scar that breaks down again and again
- New pain, a foul smell or heavy discharge in a long-standing wound
- A firm, enlarged lymph node in the groin or behind the knee
If you are already under treatment for non-healing ulcer care in Saurashtra, see Non-healing ulcer care in Saurashtra, and raise any of these signs at your next dressing review rather than waiting.
| Sign | Action | Timeline |
|---|---|---|
| Ulcer not smaller after 12 weeks of correct treatment | Specialist review and biopsy considered | At the 12-week review |
| Raised, rolled or hard edges | Biopsy from the edge | Within 2 weeks |
| Bleeds on touch or keeps growing | Biopsy from the edge and the most suspicious area | Within 2 weeks |
| New lump or sore in an old burn scar | Biopsy, even if small | Within 2 weeks |
| Enlarged lymph node with any of the above | Biopsy plus examination and scan of the nodes | Urgently, within days |
How is the biopsy taken and how long do results take?
A biopsy takes a small piece of tissue under local anaesthetic, usually in a few minutes in the clinic, and the sample is examined under a microscope by a pathologist. Results usually take about a week, depending on the laboratory. Knowing when to biopsy a non healing ulcer matters only if the sample is taken from the right place, so technique counts.
- Local anaesthetic is injected around the area, so the procedure itself should not hurt.
- Samples are taken from the edge, where ulcer meets normal skin, because that is where a cancer is most likely to show. The centre of an ulcer often contains only dead tissue.
- More than one sample is taken from large ulcers, from different parts of the edge and from any lump.
- The site is closed with a stitch or two, or dressed, and the ulcer care continues as before.
- The result is discussed in person or on a video call, along with the plan.
DermNet notes that an early sample can be misread, because healing skin can look abnormal under the microscope. If the result is reassuring but the ulcer still looks suspicious, a repeat biopsy is reasonable.
What treatment follows if cancer is found?
Surgical removal of the cancer with a margin of healthy tissue around it, called wide local excision, is the main treatment. Before surgery, the nearby lymph nodes and the depth of the tumour are checked, so the operation removes everything in one plan.
- Staging first: examination of the lymph nodes, and an MRI or CT scan if the tumour may reach muscle or bone.
- Wide local excision: the tumour is removed with a rim of normal tissue, and the edges are checked by the pathologist.
- Lymph node assessment: sentinel node biopsy or node surgery may be added for aggressive cancers or enlarged nodes.
- Bone involvement: if the cancer has reached bone, more extensive surgery is needed, and in some cases the limb cannot be saved.
- Follow-up: regular checks for at least three years, because recurrence after surgery is common, reported at 20 to 30% within three years.
Dr. Ashutosh Shah on the surgical plan: in our practice the margin of excision is decided from the biopsy findings and the depth seen on scans, and the reconstruction is planned at the same time, so that the cancer is removed completely and the wound is closed in the same operation wherever it is safe to do so.
What is Marjolin's ulcer and how is it treated?
It is a skin cancer arising in an old scar or chronic wound, most often squamous cell carcinoma. It is confirmed by biopsy and treated by wide surgical excision, with lymph node assessment and reconstruction. Radiotherapy and chemotherapy are not usually curative on their own.
How is the area reconstructed afterwards?
The wound left after excision is closed with a skin graft, a local flap or a free flap, depending on its size, depth and what lies underneath. The aim is durable skin that will not break down again.
- Skin graft: a thin layer of skin, usually from the thigh, laid over a clean wound bed with a good blood supply. See Skin grafting after excision.
- Local flap: nearby skin and tissue moved with its own blood supply, used where tendon or bone is exposed.
- Free flap: tissue moved from elsewhere in the body, with its vessels joined under a microscope, for large or deep defects, especially near the ankle.
- Scar tissue is avoided: the old burn scar around the cancer is often removed too, because it heals poorly and could break down again.
Grafted or flapped skin needs protection for some weeks. The leg is kept raised at first, and walking is increased in stages as the reconstruction settles.
Patients from Jetpur: Elegance Clinic operates in Surat only, with no branch or visiting centre in Jetpur. Send clear photographs of the ulcer and any previous reports first, so the visit can be used for examination and, if needed, the biopsy.
Next step: if an ulcer has failed three months of correct treatment, or an old scar has changed, do not wait for another dressing cycle. Book a wound review and bring photographs and previous reports.
This page is for education and is not a substitute for examination. Whether a biopsy is needed, and how any cancer is treated, is decided by your treating surgeon after examination and pathology. In an emergency, go to the nearest hospital first.
FAQs
Is a biopsy of a leg ulcer painful?
The biopsy itself should not hurt, because the area is numbed with local anaesthetic first. Most people feel a brief sting from the injection, then only pressure. The site may be sore for a day or two afterwards, which simple pain relief usually controls.
Can a biopsy make the ulcer worse?
Rarely. The sample is small and taken under clean conditions, and the site is closed or dressed. A biopsy does not cause a cancer to spread. The real risk lies in delaying a biopsy, because a cancer that is missed keeps growing while ordinary dressings continue.
How common is cancer in a chronic ulcer?
It is uncommon. Most chronic leg ulcers are caused by vein disease, poor circulation, pressure or diabetes, not cancer. Cancer is more likely in ulcers inside old burn scars, where about 2% of scars are estimated to change. That is why an ulcer that fails treatment deserves a biopsy.
What is Marjolin's ulcer?
Marjolin's ulcer is a skin cancer, usually squamous cell carcinoma, that develops in an old scar or long-standing wound. It most often arises in burn scars, on average about 30 years after the burn. It shows as a sore that will not heal, with raised edges, bleeding or a growing lump.
Does a burn scar from childhood carry risk?
A small one. Most burn scars never change. The risk rises when a scar keeps breaking down, stays open, or develops a new lump, sometimes decades later. Watch an old burn scar for any sore that does not heal within a few weeks, and have that change examined.
Which doctor should read the biopsy?
A histopathologist reads the biopsy under a microscope. The treating surgeon takes the sample, explains the result and plans treatment. If a sore in an old scar is not healing, an old burn scar ulcer doctor in Morbi or elsewhere should refer it to a plastic or reconstructive surgeon.
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