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
color,
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

Before a skin biopsy, tell your doctor
if you:

  • Are taking any medicines, particularly
    anti-inflammatory medicines such as prednisone. Anti-inflammatory medicines may
    change the way your biopsy looks under the microscope.
  • Are allergic
    to any medicines.
  • Take a blood thinner, or if you have had bleeding problems.
  • Are or might be pregnant.

No special preparation is needed before having this
test.

You may be asked to sign a consent form that says you understand the
risks of the test and agree to have it done.

Talk to your doctor
about any concerns you have regarding the need for the test, its risk, how it
will be done, or what the results will mean. To help you understand the
importance of this test, fill out the
medical test information form (What is a PDF document?).

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.

  • 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.

After the procedure

Your doctor will give you
specific instructions on how to care for your biopsy site. Keep the biopsy site
clean and dry until it heals completely.

Your stitches will be
taken out 3 to 14 days after the biopsy, depending on the biopsy site. Adhesive
bandages should remain in place until they fall off. This usually takes from 7
to 14 days.

The biopsy site may be sore or bleed slightly for
several days. Ask your doctor how much bleeding or other drainage is expected.
Call your doctor immediately if you have:

  • Excessive bleeding or drainage through the
    bandage. If excessive bleeding occurs, apply pressure to the biopsy site and
    contact your doctor.
  • Increased tenderness, pain, redness, or swelling at the biopsy
    site.
  • A fever.

Results

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

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

Skin biopsy
Normal:

The skin sample consists of normal skin
tissue.

Abnormal:

Noncancerous (benign) growths are seen.
Benign growths do not contain cancer cells. Benign skin changes include moles,
skin tags,
warts,
seborrheic keratoses,
keloids,
cherry angiomas, and benign skin tumors, such as
neurofibromas or dermatofibromas.

Cancer cells such as
basal cell cancer,
squamous cell cancer, or
melanoma are present.

Other diseases such as
lupus,
psoriasis, or
vasculitis are present.

A
bacterial or
fungal infection is present.

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

What Affects the Test

Taking medicines, such as
anti-inflammatory medicines, those used for fungal infections (antifungal
medicines), and
corticosteroid skin creams, can interfere with your
test or the accuracy of the results.

What To Think About

  • If the biopsy contains cancer cells, more
    surgery will be needed to remove the cancer completely.
  • If the
    biopsy is done on your face, you may want to have it done by a doctor who
    specializes in surgical techniques that can minimize scarring, such as a
    plastic surgeon or
    dermatologist.
  • Further testing may be
    needed if:

    • A small biopsy does not contain enough
      cells to make an accurate diagnosis.
    • Cells from the abnormal area
      weren’t included in the sample.
    • The growth or skin rash changes after the first biopsy.

References

Other Works Consulted

  • Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.

Credits

ByHealthwise Staff
Primary Medical Reviewer Kathleen Romito, MD – Family Medicine
Adam Husney, MD – Family Medicine
E. Gregory Thompson, MD – Internal Medicine
Martin J. Gabica, MD – Family Medicine
Specialist Medical Reviewer Amy McMichael, MD – Dermatology

Current as ofOctober 9, 2017