Tests and diagnosis

By Mayo Clinic Staff

Skin cancer screening

Ask your doctor whether you should consider periodic screening for skin cancer. You and your doctor may consider screening options such as:

  • Skin exams by a trained professional. During a skin exam, your doctor conducts a head-to-toe inspection of your skin.
  • Skin exams you do at home. A self-exam may help you learn the moles, freckles and other skin marks that are normal for you so that you can notice any changes. It's best to do this standing in front of a full-length mirror while using a hand-held mirror to inspect hard-to-see areas. Be sure to check the fronts, backs and sides of your arms and legs. In addition, check your groin, scalp, fingernails, soles of your feet and spaces between your toes.

Some groups recommend periodic skin exams by your doctor and on your own. Other groups don't recommend skin cancer screening exams because it's not clear whether screening saves lives. Instead, finding an unusual mole could lead to a biopsy, which, if the mole is found to not be cancerous, could lead to unnecessary pain, anxiety and cost. Talk to your doctor about what screening is right for you based on your risk of skin cancer.

Diagnosing melanoma

Sometimes cancer can be detected simply by looking at your skin, but the only way to accurately diagnose melanoma is with a biopsy. In this procedure, all or part of the suspicious mole or growth is removed, and a pathologist analyzes the sample. Biopsy procedures used to diagnose melanoma include:

  • Punch biopsy. During a punch biopsy, your doctor uses a tool with a circular blade. The blade is pressed into the skin around a suspicious mole, and a round piece of skin is removed.
  • Excisional biopsy. In this procedure, the entire mole or growth is removed along with a small border of normal-appearing skin.
  • Incisional biopsy. With an incisional biopsy, only the most irregular part of a mole or growth is taken for laboratory analysis.

The type of skin biopsy procedure you undergo will depend on your situation. Doctors prefer to use punch biopsy or excisional biopsy to remove the entire growth whenever possible. Incisional biopsy may be used when other techniques can't easily be completed.

Melanoma stages

If you receive a diagnosis of melanoma, the next step is to determine the extent (stage) of the cancer. To assign a stage to your melanoma, your doctor will:

  • Determine the thickness. The thickness of a melanoma is determined by carefully examining the melanoma under a microscope and measuring it with a special tool (micrometer). The thickness of a melanoma helps doctors decide on a treatment plan. In general, the thicker the tumor, the more serious the disease.
  • See if the melanoma has spread. To determine whether your melanoma has spread to nearby lymph nodes, your surgeon may use a procedure known as a sentinel node biopsy.

    During a sentinel node biopsy, a dye is injected in the area where your melanoma was removed. The dye flows to the nearby lymph nodes. The first lymph nodes to take up the dye are removed and tested for cancer cells. If these first lymph nodes (sentinel lymph nodes) are cancer-free, there's a good chance that the melanoma has not spread beyond the area where it was first discovered.

    Cancer can still recur or spread, even if the sentinel lymph nodes are free of cancer.

Other factors may go into determining the aggressiveness of a melanoma, including whether the skin over the area has formed an open sore and how many dividing cancer cells are found when looking under a microscope.

Melanoma is staged using the Roman numerals I through IV. A stage I melanoma is small and has a very successful treatment rate. But the higher the numeral, the lower the chances of a full recovery. By stage IV, the cancer has spread beyond your skin to other organs, such as your lungs or liver.

Apr. 15, 2014

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