A skin biopsy is a short procedure in which a doctor numbs a small patch of skin with an injection, then removes a sample of a spot, or sometimes the whole spot, so it can be examined under a microscope. You stay awake throughout. Once the injection has worked, you should feel little or no pain.
- A biopsy shows for certain what a spot is, including whether it is a skin cancer.
- The three main types are punch, shave and excision, chosen according to what the spot might be and where it is.
- The anaesthetic injection stings briefly. After that, most people feel little or no pain.
- Keep the dressing dry for 48 hours, and call if the wound becomes hot, red or swollen or leaks pus.
- The team who did your biopsy will tell you when to expect results.
Why would I need a skin biopsy?
You need a biopsy when a doctor can’t be sure what a spot is just by looking at it. The sample goes to a pathologist, a doctor who examines tissue under a microscope, who can say whether it is harmless, precancerous or a skin cancer such as a basal cell carcinoma, squamous cell carcinoma or melanoma. There is a separate guide to the role of histopathology if you’d like to know what happens to the sample in the laboratory.
What are the main types of skin biopsy?
Which type you have depends on what the doctor thinks the spot might be, how big it is and where it sits. This clinical overview has the medical detail.
Punch biopsy
The doctor presses a small round blade, a bit like a tiny pastry cutter, onto the skin and turns it to lift out a narrow core through all its layers. The small hole is usually closed with a stitch or a paper strip.
Shave biopsy
The doctor uses a fine blade to shave off the raised part of a spot, level with the surrounding skin or just below it. There are usually no stitches, and the wound heals under a dressing. Shave biopsies aren’t used when a spot might be a melanoma, because the pathologist needs to see how deep a melanoma goes.
Excision biopsy
The doctor removes the whole spot with a small margin of normal-looking skin, usually as a narrow oval so the wound closes into a straight line of stitches. This is the usual choice when a mole might be a melanoma, because the pathologist can then measure its thickness. For a large spot, the doctor sometimes removes only part of it (an incisional biopsy).
What happens at the appointment, and does it hurt?
Most skin biopsies are done in a clinic room under local anaesthetic, and you go home the same day. The appointment usually runs like this:
- The doctor explains why the biopsy is needed and the risks, such as bleeding, infection and scarring, and asks for your consent.
- You are asked about allergies and about any medicines that thin your blood. The spot may be photographed.
- The team checks your name, the spot and the procedure, sometimes more than once. This is a standard safety check.
- The doctor injects local anaesthetic around the spot. This stings briefly, and then the skin goes numb.
- The sample is taken, the wound is closed or dressed, and the sample goes to the laboratory.
Once the skin is numb, the biopsy itself shouldn’t hurt. Some soreness for a day or two afterwards is normal, as is numbness or tingling around the wound, which usually settles on its own.
If you take a blood thinner, tell the team beforehand, but never stop it without advice from the doctor who prescribes it. The guide to preparing for a biopsy covers this and more.
Having a biopsy on your nose or face
A biopsy on the nose, eyelid, lip or ear needs more planning, because these areas have little spare skin and a badly placed wound can pull them out of shape. The doctor works out how the wound will close before taking the sample, and lines the cut up with the natural creases of your skin where possible so the scar is finer. If the spot is large, or sits on the edge of an eyelid or lip or on the tip of the nose, you may be referred to a surgeon who does facial reconstruction first, so the repair is planned from the start.
How do I look after the wound?
Keep the dressing on and dry for the first 48 hours, and avoid exercise and heavy lifting during that time. After that, clean the area gently with clean water or salt water and put on a fresh plain dressing until it has healed or your stitches are out. Don’t swim or soak the wound in a bath until it has fully healed.
After a biopsy on the lower leg, keep the leg raised as much as you can for a day or two. Stitches on the face usually come out after five to seven days and stay in longer elsewhere, so your team will tell you when yours are due. Every biopsy leaves some scar, and if yours becomes thick and raised, mention it at your follow-up appointment.
Warning signs to call about
Problems after a skin biopsy are uncommon. If you notice any of these, contact the team who did your biopsy or your GP, or call NHS 111 if you can’t reach them:
- redness or warmth spreading out from the wound
- pus or discharge from the wound
- a high temperature
- pain that is getting worse rather than better
- bleeding that doesn’t stop when you press firmly on the dressing
- the wound opening up
How do biopsy results come back?
Your results come back once a pathologist has examined the sample and a clinician has reviewed the report, so there is no answer on the day. How long that takes depends on the laboratory, and the team who did your biopsy will tell you when to expect them. If that date passes without news, call and ask.
What happens if the biopsy shows skin cancer?
The next step depends on exactly what the report shows:
- If the spot is harmless (benign), often nothing more is needed.
- If it is precancerous, such as actinic keratosis, Bowen’s disease or lentigo maligna, your specialist will talk you through the treatment options.
- If it is a basal cell or squamous cell carcinoma, further treatment is usually arranged to remove it completely.
- If it is a melanoma, you will be referred urgently to a specialist skin cancer team.
- If the result is unclear, a second biopsy is sometimes needed.
For a basal cell or squamous cell carcinoma on the face, or anywhere saving healthy skin matters, you may be offered Mohs surgery. The surgeon removes the cancer in thin layers and checks each one under the microscope during the operation, stopping once the edges are clear.
On the nose, eyelids or lips, the wound sometimes needs more than a simple line of stitches to close neatly, and that repair is called reconstruction. The guide to skin cancer detection covers the wider pathway.
Talking to Miss Nayar
Miss Rakhee Nayar is a Consultant Plastic Surgeon, FRCS (Plast), MD, and one of fewer than 10 women in the UK dual-trained in both plastic surgery and Mohs micrographic surgery. She sees patients for diagnosis and treatment of skin lesions, including Mohs surgery and reconstruction after skin cancer removal, at Circle Cheshire Clinic and Fairfield Independent Hospital. If you have a biopsy result to talk through or a spot that worries you, you can contact her team.
Frequently asked questions
Does a skin biopsy hurt?
Most people only feel the local anaesthetic injection, which stings briefly. After that the area is numb and the biopsy itself shouldn’t hurt, though you can expect some soreness for a day or two.
How long do skin biopsy results take?
It depends on the laboratory, so the team who did your biopsy will tell you when to expect them. Results are never immediate, because a pathologist has to examine the tissue and a clinician then reviews the report.
Why might my GP refer me instead of doing a biopsy?
If a spot looks like it could be a melanoma, or a fast-growing, firm or ulcerated lump on the head or neck, your GP will usually refer you urgently rather than take a sample. A specialist can then remove the whole spot without the delay of a partial sample first. The guide to referral criteria explains when this happens.
Recommended
- Skin cancer symptoms and signs: the UK guide for early detection
- How to prepare for a skin cancer biopsy
- Skin cancer specialist referral criteria: a UK patient guide
- Role of histopathology in skin cancer: a clinical guide
Filed under Spotting Skin Cancer
