Diagnosing Metastatic Melanoma: What You Need to Know

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We all know to be on the lookout for skin cancer -- particularly melanoma, the dangerous type of skin cancer. Nevertheless, melanoma often avoids detection until it has spread to other parts of the body; then it's known as metastatic melanoma. When this happens, the symptoms of melanoma may be different than those of other skin cancers, going beyond a visual change to the skin.

Signs of Metastatic Melanoma

  • A sore. Melanoma starts as a spot on the skin that may resemble a mole. But unlike a normal mole, melanoma will change in shape, size, color, and texture over time. As the cancer begins to penetrate the lower layers of the skin, it may cause a sore that is red, swollen, or painful to the touch. But unlike other sores, this one will not heal in a week or two.
  • A lump. One of the first places melanoma typically spreads is to the lymph nodes, and when this happens it may cause a lump, often in the neck, collarbone, shoulder area, armpit, or groin.
  • Symptoms elsewhere in the body. In addition to the lymph nodes, melanoma can spread to the lungs, liver, brain, and other organs, causing additional symptoms specific to those areas of the body.

Tests for Metastatic Melanoma

Early-stage melanoma is diagnosed using various types of skin biopsies to take samples of the suspicious skin tissue. If possible, the doctor will do an excisional biopsy, which removes the entire skin tumor.

A fact that may surprise you is that 7 percent of melanoma tumors aren't in the skin but instead occur in the eye, inside the nose, and in the tissues lining the mouth, vagina, anus, and rectum. Diagnosing metastatic melanoma requires going beyond skin tests to investigate how far the cancer has spread.

To check for cancer cells in the lymph nodes, the doctor will press or "palpate" your lymph nodes, looking for swelling or tenderness. Your doctor will also biopsy the sentinel node, which is the first stop for cancer cells in the lymphatic system. Any other suspicious nodes will also be biopsied, and your doctor may remove one or more lymph nodes altogether if necessary.

A pathologist then studies the biopsy samples, looking at the thickness of the tumor and the speed with which cancer cells are dividing (known as the mitotic rate). Most likely the doctor will also order a blood test for genetic mutations that are present in more than half of all metastatic melanomas. Another blood test can be used to detect LDH (lactate dehydrogenase), which is an indicator of how metastatic melanoma is likely to respond to treatment.

Your doctor will order a number of imaging tests, which may include X-rays, PET and CT scans, and MRIs, to check your lungs, brain, bones, and internal organs to make sure they are clear of cancer.

The results of these tests will give your medical team as complete a picture as possible of how the cancer has affected your body. Based on these results, your oncologist will stage the cancer, which is key to determining the right course of treatment. Metastatic melanoma can either be stage III, which means the cancer has spread to the lymph nodes, or stage IV, in which cancer has spread to other parts of the body.

Within stage III there are three sub-stages (IIIA, B, and C), which all have different indications, treatment regimens, and survival rates, so be sure to pay attention to all the information your doctor gives you about the stage of your cancer.

While metastatic melanoma is more serious than melanoma diagnosed at an earlier stage, there is an extensive arsenal of treatments available to fight it. And in the past few years, the number of available treatment options has expanded rapidly, with still more undergoing clinical trials.

Melanie Haiken

Melanie Haiken discovered how important it is to provide accurate, targeted, usable health information to people facing difficult decisions when she was health editor of Parenting magazine. See full bio