What is a skin biopsy?

A skin biopsy is a procedure that removes a small sample of skin for testing. The skin sample is looked at under a microscope to check for a variety of conditions, including skin cancer.

There are three main ways to do a skin biopsy. The type of biopsy you get depends on the location and size of the abnormal area of skin, known as a skin lesion. These types include:

• A punch biopsy, which uses a special tool with a round blade to remove a small, round piece of skin. This may be used to get a sample that goes deeper into the skin.
• A shave biopsy, which removes a sample from the topmost layers of your skin with a razor blade. This is the most used of the three types.
• An excisional biopsy, which removes the skin sample with a small knife called a scalpel (a small cutting blade).

Most skin biopsies can be done in a health care provider's office or other outpatient facility.

Other names: punch biopsy, shave biopsy, excisional biopsy, skin cancer biopsy, basal cell biopsy, squamous cell biopsy, melanoma biopsy

What is it used for?

A skin biopsy is used to help diagnose a variety of skin conditions including:

• Skin disorders such as psoriasis and eczema
• Bacterial or fungal infections of the skin

A provider can also use a skin biopsy to see if a suspicious mole or other growth is cancerous. Because skin cancer is the most common type of cancer in the United States, it is important for providers to check for skin cancer often. Its most common types are:

• Squamous cell carcinoma. This type forms in the upper parts of the epidermis (the topmost layer of the skin) and rarely spreads. It's most often found in sun-exposed parts of the body such as your face, arms, and hands.
• Basal cell carcinoma. This type forms in the basal cell layer (the lower parts) of the epidermis and also rarely spreads. This is the most common type of skin cancer and usually forms on the face, head, neck, and arms.
• Melanoma. This type forms in the cells that make your skin's pigment (or color). These cells also protect deeper layers of the skin from some of the sun's harmful effects. It is less common than the other two, but also more dangerous. This is because it is more likely to spread.

If your provider thinks you may have basal or squamous cell carcinoma, they may perform a punch or shave biopsy. If they think you may have melanoma, they will likely perform an excisional biopsy to make sure they remove all of the suspicious tissue.

Why do I need a skin biopsy?

You may need a skin biopsy if you have certain skin symptoms such as:

• A persistent rash.
• Scaly or rough skin.
• Open sores that won't heal.
• Blistering skin, which may be a sign of pemphigus, an autoimmune disease.
• A mole or new growth that has the "A-B-C-D-Es" of melanoma:
  • Asymmetrical -- the shape is not regular.
  • Border -- the edge is jagged.
  • Color -- the color is uneven.
  • Diameter -- the size is larger than a pea.
  • Evolving -- the mole or growth has changed in the past few weeks or months.

What happens during a skin biopsy?

A provider will clean the site and inject an anesthetic (medicine) so you won't feel any pain during the procedure. The rest of the procedure steps depend on which type of skin biopsy you are getting:

Punch biopsy

• A provider will place a special circular tool over the abnormal skin area (lesion) and rotate it to remove a small piece of skin (about the size of a pencil eraser).
• The sample will be lifted out with a special tool.
• If a larger skin sample was taken, you may need one or two stitches to cover the biopsy site.
• Pressure will be applied to the site until the bleeding stops.
• The site will be covered with a bandage or sterile dressing.

Shave biopsy

• A provider will use a razor or a scalpel to remove a sample from the top layer of your skin.
• Pressure will be applied to the biopsy site to stop the bleeding. You may also get a medicine that goes on top of the skin (also called a topical medicine) to help stop the bleeding.

Excisional biopsy

• A surgeon will use a scalpel to remove the entire skin lesion (the abnormal area of skin).
• The surgeon will close the biopsy site with stitches.
• Pressure will be applied to the site until the bleeding stops.
• The site will be covered with a bandage or sterile dressing.

After the biopsy, keep the area covered with a bandage until you've healed, or until your stitches come out. If you had stitches, they will be taken out 3-14 days after your procedure.

Will I need to do anything to prepare for the test?

You don't need any special preparations for a skin biopsy.

Are there any risks to the test?

You may have a little bruising, bleeding, or soreness at the biopsy site. If these symptoms last longer than a few days or they get worse, talk to your provider.

What do the results mean?

If your results were normal, it means no cancer or skin disease was found. If your results were not normal, you may be diagnosed with one of the following conditions:

• A bacterial or fungal infection.
• A skin disorder such as psoriasis.
• Skin cancer. Your results may mean you have one of three types of skin cancers: basal cell, squamous cell, or melanoma.

If you are diagnosed with basal cell or squamous cell cancer, the entire cancerous lesion may be removed at the time of the skin biopsy or soon after. Often, no other treatment is needed. If you are diagnosed with melanoma, you will need more tests to see if the cancer has spread. Then you and your provider can develop a treatment plan that's right for you.

Learn more about laboratory tests, reference ranges, and understanding results.