What is a skin biopsy?

A skin biopsy is a procedure that removes a small sample of skin for testing. The procedure can help diagnose a skin lesion (an abnormal area of skin). The skin sample is looked at under a microscope to check for skin cancer, a variety of skin conditions, or skin infections. Only certain skin lesions need a biopsy. Your provider may be able to diagnose many types of lesions just by looking at them.

There are three main ways to do a skin biopsy. The type of biopsy you have depends on the location, size, and depth of the skin lesion:

• A shave biopsy removes a sample from the top layers of skin with a razor blade or scalpel (a small cutting blade used for surgery). Your provider will do a shave biopsy if your condition appears to involve only the top layers of skin.
• A punch biopsy uses a special tool with a round blade to remove the skin sample. Your provider will do a punch biopsy if your condition appears to involve the deep layers of skin.
• An excisional biopsy uses a scalpel to remove all of the skin lesion, usually with some normal skin around it. The sample may include the full thickness of the skin along with fat below the skin.

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, eczema, actinic keratosis ("precancers"), and warts.
• Bacterial or fungal infections of the skin.
• Skin cancer. A biopsy can confirm or rule out whether a suspicious mole or other growth is cancer. If the result is cancer, the biopsy can show what type of skin cancer it is.

Skin cancer is the most common type of cancer in the United States. The two most common types of skin cancer are basal cell and squamous cell cancers. These cancers rarely spread to other parts of the body and can usually be cured with treatment. In many cases, the biopsy removes all the cancer, and no other treatment is needed.

The most serious type of skin cancer is melanoma. It's more likely than other skin cancers to spread to other parts of your body, including to your organs. Most deaths from skin cancer are caused by melanoma.

A skin biopsy can help diagnose skin cancer in the early stages, when it's easier to treat.

Why do I need a skin biopsy?

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

• A rash that doesn't go away
• Scaly or rough skin
• Open sores that won't heal
• A mole or skin growth that has changed in its shape, color, or size
• 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
• Blistering skin, which may be a sign of pemphigus, an autoimmune disease

What happens during a skin biopsy?

A provider will clean the site and give you an injection (shot) to numb your skin so you won't feel any pain.

For a punch biopsy:

• A provider uses a special tool with a hollow, round blade. The blade is placed over the abnormal skin area (lesion) and rotated to remove a small piece of skin about the size of a pencil eraser.
• The sample is lifted out with another tool.
• If a larger skin sample is taken, you may need one or two stitches to close the wound.
• Pressure will be applied to the wound until the bleeding stops.
• The wound will be covered with a bandage.

A punch biopsy is often used to diagnose rashes.

For a shave biopsy:

• A provider will use a razor or a scalpel to remove a sample from the top layer of your skin.
• To help stop the bleeding, pressure will be applied to the wound, or medicine may be spread over the wound.
• The wound will be covered with a bandage.

A shave biopsy is often used if your provider thinks you may have basal cell or squamous cell skin cancer or if you have a rash appears to affect only the top layer of your skin.

For an excisional biopsy:

• A doctor will use a scalpel to remove the entire skin lesion, usually with some normal skin around it called "a margin." If the skin lesion is large, your provider may remove only a piece of it. This is called an incisional biopsy.
• The doctor will close the wound with stitches.
• Pressure will be applied to wound until the bleeding stops.
• The wound will be covered with a bandage.

An excisional biopsy is often used if your provider thinks you may have melanoma, the most serious type of skin cancer. It may also be used for basal cell and squamous cell skin cancer.

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 the biopsy.

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, tell your provider.

Infection is possible, so it's important to keep the wound clean until it heals. Your provider will tell you how to care for your wound. You may have a scar after healing.

What do the results mean?

A normal biopsy result means no cancer or skin disease was found.

An abnormal biopsy result may diagnose a specific skin condition. But sometimes abnormal results aren't clear, and you may need more tests to find out exactly what condition you have. Your provider can explain what your results mean.

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

Is there anything else I need to know about a skin biopsy?

If your provider thinks you may have a basal cell or squamous cell cancer, the entire lesion may be removed during the biopsy. Often, the biopsy removes the entire cancer and 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 health care provider can develop a treatment plan that's right for you.