Test Overview

A skin biopsy is a procedure in which a sample of skin tissue is removed, processed, and examined under a microscope.

Several different methods may be used to obtain a skin sample, depending on the size and location of the abnormal area of skin, called a skin lesion. The skin sample is placed in a solution, such as formaldehyde, or in a sterile container if infection is suspected. In each of these procedures, the tissue is processed and then examined under a microscope.

Skin biopsies most often are done to diagnose skin cancer, which may be suspected when an abnormal area of skin has changed colour, shape, size, or appearance or has not healed after an injury. Skin cancers are the most common type of cancers.

Early diagnosis of a suspicious skin lesion and skin biopsy can help identify skin cancers and lead to early treatment.

Why It Is Done

A skin biopsy is done to diagnose a:

• Skin condition (if it is not already clear what the condition is), such as psoriasis.
• Disease, such as skin cancer.
• Bacterial or fungal skin infection.

How To Prepare

In general, there's nothing you have to do before this test, unless your doctor tells you to.

• If you are taking any medicines, particularly anti-inflammatory medicines such as prednisone, talk to your doctor. Anti-inflammatory medicines may change the way your biopsy looks under the microscope.
• If you take aspirin or some other blood thinner, ask your doctor if you should stop taking it before your procedure. Make sure that you understand exactly what your doctor wants you to do. These medicines increase the risk of bleeding.

How It Is Done

Usually the place where the biopsy will be taken is cleaned with an alcohol wipe. A marker may be used to outline the edges of the skin sample. For some biopsies, a surgical drape is used to cover the area around the biopsy and the doctor will wear a mask, gown, and gloves.

Several different methods may be used to obtain a skin sample, depending on the size and location of the skin lesion. The skin sample is placed in a solution, such as formaldehyde, or in a sterile container if infection is suspected. In each of these procedures, the tissue is then examined under a microscope.

Skin biopsy methods include:

Shave biopsy.

After a local anesthetic is injected, a surgical knife (scalpel) is used to shave off the growth. Stitches are not needed. Any bleeding can usually be controlled with a chemical that stops bleeding and by applying pressure. The biopsy site is then covered with a bandage or sterile dressing.

Punch biopsy.

After a local anesthetic is injected, a small, sharp tool that looks like a cookie cutter (punch) is placed over the lesion, pushed down, and slowly rotated to remove a circular piece of skin. The skin sample is lifted up with a tool called a forceps or a needle and is cut from the tissue below. Stitches may not be needed for a small skin sample. If a large skin sample is taken, one or two stitches may be needed. Pressure is applied to the site until the bleeding stops. The wound is then covered with a bandage or sterile dressing.

Excision.

After a local anesthetic is injected, the entire lesion is removed with a scalpel. Stitches are used to close the wound. Pressure is applied to the site until the bleeding stops. The wound is then covered with a bandage or sterile dressing. If the excision is large, a skin graft may be needed.

How It Feels

You will feel brief stinging pain when the local anesthetic is injected. You should not feel any pain when the skin sample is removed.

Risks

Although unlikely, there is a slight risk of infection and a slight risk of persistent bleeding. If you usually form scars after skin injuries or surgery, you could develop a scar at the biopsy site.

Results

Results from a skin biopsy usually are available in 3 to 10 days.

Your doctor will talk with you about any abnormal results that may be related to your symptoms and past health.