Skin Biopsy: What to Expect Before, During and After

Being told you need a skin biopsy can feel like a big step, even though the procedure itself is usually small. Most people want to know the same few things: will it hurt, will it scar, and how long will the wait be? This page describes what major medical sources say about each of those. It is general information only. Your own clinician decides the type of biopsy, and the aftercare instructions you are given should always take priority over anything written here.

Why a biopsy is done

A skin biopsy removes a small piece of skin so that it can be studied under a microscope. The American Academy of Dermatology (AAD) says it is usually done in an office visit while you stay awake, and that looking at the tissue under a microscope is the only way to diagnose some conditions, including certain skin cancers, infections and blistering diseases (AAD: What is a skin biopsy?). A biopsy is therefore not only about cancer. It can also help explain a rash that other tests have not settled, a step described in the wider guide to how dermatologists diagnose skin conditions.

The main types of skin biopsy

Which type is used depends on the problem and the part of the body. The AAD lists five main methods. In a shave biopsy, a razor-like tool removes a thin layer from the top of a growth. A punch biopsy uses a tube-shaped tool, rather like a cookie cutter, to take a sample that includes several skin layers. Surgical scissors can snip off a growth that hangs from the skin, and a curette, a loop-tipped tool, scrapes a growth away. Excisional and incisional biopsies use a scalpel; an excision removes the whole growth, while an incisional biopsy removes only part of it.

Mayo Clinic describes three of these in similar terms, and adds that the type you have depends on your symptoms and where on the body the procedure is done (Mayo Clinic: Skin biopsy). DermNet, a dermatology reference, gives more detail on size. A punch tool takes a round sample of 2 to 6 mm, with 3 and 4 mm the most common, and it makes a small wound. A shave biopsy is a superficial cut and does not include the full thickness of the skin, so DermNet notes it may not rule out invasive disease. A larger, deeper excision removes the lesion with a surrounding margin (DermNet: Skin biopsy).

Numbing and what you may feel

The skin is cleaned and numbed with a local anaesthetic injection. According to the AAD, the injection may cause burning or stinging, and a curette biopsy may not need one. Mayo Clinic says the numbing medicine can cause a burning feeling for a few seconds, after which you should not feel any pain during the biopsy. DermNet says the injection stings transiently.

The NHS adds that most biopsies use a local anaesthetic, so you stay awake without feeling pain, and that sedation is sometimes offered to help people relax. (NHS: Biopsy). Mayo Clinic says a skin biopsy itself takes about 15 minutes. DermNet notes that fainting is more common than a true allergy to the anaesthetic, which it calls extremely rare.

Stitches and wound care

A shave biopsy does not require stitches according to DermNet, whereas incisional and excisional biopsies usually do. A punch biopsy wound may be closed with a stitch or may heal without one. After the sample is taken, bleeding is controlled with pressure or medicine, and the wound is covered.

The advice on caring for the wound varies, which is why your own instructions matter most. The AAD says the wound is covered with petroleum jelly and a bandage, kept covered for as long as your dermatologist recommends, with daily cleaning, a fresh thin layer of petroleum jelly and a new bandage. Mayo Clinic describes a similar routine and suggests covering the site with a bandage for 2 to 3 days, continuing wound care until any stitches are removed. The NHS says that if you have stitches or a dressing, the healthcare team will tell you how to look after the wound at home. DermNet says a shave biopsy wound forms a scab and should heal in 1 to 3 weeks.

Some pain afterwards is expected. Mayo Clinic says mild pain can be expected and is usually controlled with pain relievers. Both Mayo Clinic and the NHS list signs that should prompt contact with the healthcare team: fever, increased pain, swelling or redness, or fluid or blood oozing from the site. A fuller discussion of general wound care appears in wound and scar care alongside physical therapy.

Scarring

Any biopsy that cuts the skin can leave a mark. DermNet says a significant permanent scar is usual after the larger procedures, and that a scoop (deep shave) biopsy can scar more if it is left to heal on its own. Mayo Clinic says some people develop a thick, raised scar called a keloid, which is more common in people with brown or Black skin and when the biopsy is on the neck, back or chest. If scarring concerns you, raise it before the procedure.

How long results take, and what a report is

Timing varies a great deal, and sources are candid about it. DermNet says results usually take one to two weeks, longer if special stains or second opinions are needed. Mayo Clinic says results may be available in a few days, while more technical tests take longer. The NHS says it can take a few weeks or more, depending on the hospital and the reason for the biopsy, and suggests contacting the healthcare team or GP surgery if you have heard nothing after a few weeks. These are all different healthcare settings, so your own clinic's estimate is the number to rely on.

The sample is examined in a laboratory by a pathologist, who writes a pathology report for your clinician. DermNet describes a general histopathologist or specialist dermatopathologist examining the processed sections under a light microscope, sometimes with special stains, and issuing a report with a microscopic description, the diagnosis and comments (DermNet: Dermatopathology, preparation of specimen). Your clinician then reviews the report and tells you the result. The AAD notes that if the result is negative you may not need further action, and that treatment, if needed, is arranged at a follow-up. Because a biopsy is often ordered when a spot has raised a concern about skin cancer, the page on skin cancer screening basics explains how that wider picture is viewed.

Risks as sources describe them

DermNet lists the main risks. Bleeding is more of a concern with bleeding tendencies or blood-thinning medicines such as warfarin or aspirin, so the clinician should know what you take. Infection affects about 1 to 5% of excisional biopsies and is extremely uncommon with small punch, shave or incisional biopsies. A small sensory nerve can be cut, causing pain or numbness, most likely where skin is thin, such as the face or back of the hand. The lesion may not be completely removed, and the wound can occasionally break down, especially at high-tension sites. DermNet states that the larger the sample, the higher the chance of complications. The NHS describes biopsy in general as a common and very safe procedure.

Preparing questions beforehand can make the visit calmer, and the page on preparing for a dermatology visit suggests how. Nobody should change or stop a medicine without their own clinician's advice, including blood thinners.

The short version

A skin biopsy is usually a brief office procedure done under local anaesthetic, with a small wound, simple dressings and a wait for a pathology report that varies from days to weeks. Scarring and a small risk of bleeding or infection are the main downsides sources name. Follow the instructions your own clinician gives you, and ask them anything the written leaflet leaves unclear.