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Tests and diagnosis
By Mayo Clinic staff
Skin cancer screening
The American Cancer Society (ACS) recommends having a complete skin exam every year if you're older than 40, or more often if you're at high risk of developing skin cancer. These screening exams involve a head-to-toe inspection of your skin by someone qualified to diagnose skin cancer, such as a dermatologist or nurse specialist. If you have risk factors for skin cancer — fair skin, a history of severe sunburns, one or more dysplastic moles, or a family history of melanoma — talk to your doctor about more frequent screenings. Sometimes frequent screenings are recommended for all close family members of a person with melanoma.
In addition, the ACS recommends monthly self-exams. This helps you learn the moles, freckles and other skin marks that are normal for you, so 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 and fingernails, and your soles and the spaces between your toes.
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, your doctor or dermatologist removes all or part of the suspicious mole or growth, and a pathologist analyzes the sample.
If the mole is small, your doctor is likely to perform an excisional biopsy — such as a punch biopsy or an elliptical excision. In this procedure, the entire mole or growth is removed, along with a small border of normal-appearing skin. An incisional biopsy is more likely to be used for large moles (larger than 3/8 inch, or 10 millimeters), or for those in places where scars would be more obvious. With an incisional biopsy, only the most irregular part of a mole or growth is taken for laboratory analysis. Contrary to common belief, incisional biopsies don't cause melanoma to spread.
Staging
If you receive a diagnosis of melanoma, the next step is to determine the extent, or stage, of the cancer. Melanoma is staged using these criteria:
- Thickness and depth. A pathologist determines the thickness and depth of a melanoma by carefully examining it under a microscope. The thickness of a cancerous lesion is the most important factor in deciding on a treatment plan. In general, the thicker the tumor, the more serious the disease.
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Spread. It's also important to determine whether melanoma cells have spread to your lymph nodes. To do so, your surgeon may use a procedure known as a sentinel node biopsy. Doctors are developing and evaluating criteria to determine who should undergo this procedure. Sentinel node biopsy isn't used for the most superficial forms of melanoma.
Until recently, surgeons would remove as many lymph nodes as possible to verify that the nodes didn't contain cancer cells. But this greatly increased the risk of lymphedema — severe swelling of the involved area — and other side effects. That's why a new procedure was developed that focuses on finding the sentinel nodes — the first nodes to receive the drainage from malignant tumors and therefore the first to develop cancer. If a sentinel node is removed, examined and found to be healthy, the chance of finding cancer in any of the remaining nodes is very small and no other nodes need to be removed.
Melanoma is staged using the numbers 0 through IV:
- Stage 0. This melanoma is also called in situ melanoma. At this stage, the cancer is confined to the epidermis and hasn't begun to spread. Treatment consists of complete surgical removal only. Finding and treating a cancerous tumor at this stage offers the best chance for a full recovery.
- Stages I through IV. These cancers are invasive tumors that have the ability to spread to other areas. A stage I cancer is small and well localized and has a very successful treatment rate. But the higher the stage number, 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, liver and bone. Although it may not be possible to eliminate the cancer at this stage, treatment with radiation or biological or experimental therapies may help alleviate signs and symptoms.
