Skin biopsy (punch biopsy)

A skin biopsy is primarily performed to establish a diagnosis. It does not usually remove the entire skin lesion.

When might a skin biopsy be needed?

The GP may recommend a skin biopsy if examining the skin alone does not provide enough information to determine the type of skin lesion or skin condition. Microscopic examination can help establish the diagnosis and guide further treatment.

A skin biopsy may be needed:

• if the nature of a skin lesion is unclear;
• for a persistent rash or inflammation that does not respond sufficiently to treatment;
• to distinguish between different skin conditions;
• if a particular skin disease is suspected;
• to examine the type and growth pattern of a suspicious skin lesion.

Not every skin lesion is suitable for a punch biopsy. Sometimes it is important to remove the entire lesion. The GP may then recommend an excision. A clearly benign, raised skin lesion can sometimes be removed superficially with a shave excision.

A partial punch biopsy is usually not the first choice for a mole that may be malignant. The GP will discuss the most appropriate examination, procedure or referral with you.

Initial assessment by the GP

Before a skin biopsy is scheduled, the GP will assess your skin during a regular consultation. The GP will consider:

• the appearance and location of the skin lesion;
• how long the lesion has been present;
• any changes or symptoms;
• other skin abnormalities;
• treatments you have already tried.

If a skin biopsy is appropriate, a separate appointment will be scheduled for the procedure. In some cases, the GP may first consult a dermatologist or refer you for specialist assessment.

Preparing for the procedure

Tell the GP beforehand:

• if you are allergic to local anaesthetics, disinfectants or adhesive dressings;
• if you have previously experienced problems with local anaesthesia or wound healing;
• if you have diabetes, vascular disease or a weakened immune system.

Never stop taking anticoagulants or antiplatelet medication without medical advice. These medicines usually do not need to be stopped for a minor skin biopsy. The GP will assess whether any additional precautions are required in your situation.

You may eat and drink as usual unless you have been advised otherwise. Wear loose-fitting clothing so that the area being examined is easy to access.

What happens during a skin biopsy?

The GP will carefully select the area from which the skin sample will be taken. The biopsy site may be marked or recorded in a photograph.

The following steps are then performed:

1. the skin is cleaned and disinfected;
2. you receive an injection of local anaesthetic;
3. the GP checks that the skin is sufficiently numb;
4. a small, round piece of skin is removed with a biopsy punch;
5. any bleeding is stopped;
6. the wound is closed with one stitch if necessary;
7. the wound is covered with a dressing or plaster.

A biopsy punch with a diameter of approximately 3 or 4 millimetres is usually used. Depending on its size and location, the wound may be left to heal without stitches or may be closed with one stitch.

The local anaesthetic injection may briefly cause a stinging or burning sensation. Once the anaesthetic has taken effect, you should not feel pain during the biopsy. You may still feel touch, pressure or movement.

You can go home immediately after the procedure.

Laboratory examination and results

The skin sample is sent to a pathology laboratory. A pathologist examines the tissue under a microscope. Additional stains or tests may sometimes be required.

The results are usually available within two to three weeks, although they can occasionally take longer. The GP will explain beforehand how you will receive the results.

The results may lead to:

• reassurance without further treatment;
• treatment at the GP practice;
• further investigations;
• complete removal of the skin lesion;
• referral to a dermatologist.

A skin biopsy examines only a small area of skin. It may therefore not always provide a definitive explanation for your symptoms. Further investigations or another biopsy may then be required.

After the skin biopsy

The local anaesthetic usually continues to work for several hours. The wound may feel sore once it wears off. If necessary, take paracetamol according to the instructions on the packaging.

Always follow the personal wound-care instructions provided by the GP. The following advice will usually apply:

• leave the plaster or dressing in place for as long as advised;
• replace it if it becomes wet, dirty or soaked with blood;
• keep the wound dry initially, as instructed by the GP;
• touch the wound as little as possible;
• avoid swimming and bathing until the wound has closed properly;
• avoid pulling, pressure and friction around the biopsy site;
• avoid strenuous exercise if this places tension on the wound;
• protect the treated skin from sunlight once the wound has fully closed.

If the wound has been stitched, the GP will tell you when the stitch should be removed. Depending on the location, this is usually after approximately one to two weeks.

Scarring and possible complications

A skin biopsy usually leaves a small round or linear scar. The scar may initially appear red or dark and often becomes less noticeable over the following months. A lighter, darker, raised or slightly indented mark may remain.

Possible complications include:

• bleeding after the procedure;
• bruising or swelling;
• a wound infection;
• the wound reopening;
• delayed wound healing;
• a change in skin colour;
• a noticeable or raised scar;
• altered sensation around the wound.

When should you contact the practice?

A small amount of blood or wound fluid beneath the dressing is usually not a cause for concern. If the wound starts bleeding, press firmly on it with a clean gauze pad or cloth continuously for 15 minutes.

Contact the practice the same day if:

• the wound continues to bleed despite applying firm pressure;
• the wound reopens;
• the pain clearly increases;
• the skin around the wound becomes increasingly red, warm or swollen;
• pus comes from the wound;
• you develop a fever or feel unwell;
• you are concerned about the wound for any other reason.

Outside our opening hours, contact the out-of-hours GP service if your symptoms cannot wait until the practice reopens.

Further information

Read more:

• Huidarts.com – Skin biopsy
• Huisartsvechtrijk.nl – Excision
• Huisartsvechtrijk.nl – Shave excision