Symptoms & Diagnosis

How dermatologists identify the physical characteristics of a melanoma

As you know, understanding what to look for plays an important role in the diagnosis of cutaneous (skin) melanoma. For instance, having 50 moles or more puts you at increased risk. Though many of these moles are harmless, it is critical to notice changes in their size, shape, or color since these can be signs of melanoma.

A key warning sign is a new spot or a spot that looks different from other spots on your skin. According to the American Cancer Society, the ABCDE rule can be helpful in identifying a melanoma.

  1. Asymmetry: One half of a mole or birthmark looks different from the other half
  2. Border: Irregular edges
  3. Color: Color is not consistent; may include shades of brown or black; can also be pink, red, white, or blue
  4. Diameter: Larger than ¼ inch, though melanomas may be smaller
  5. Evolving: Mole is changing size, shape, or color

Other warning signs of melanoma may include a sore that does not heal, redness or swelling, and itchiness or tenderness. Sometimes a cancerous mole will even ooze or bleed. Since there is great variability from mole to mole, it is important to talk with your doctor if you notice any of these symptoms.

With early detection and treatment, patients with cutaneous melanoma—the most aggressive type of skin cancer—have a good chance of recovery.

Only a skin biopsy can determine your diagnosis

Melanoma is diagnosed by a dermatologist who examines a patient’s skin for suspicious moles or spots. Sometimes the dermatologist will use a device called a dermoscope to magnify and shine light on the skin in order to get a better look at its pigments and structure.

If your doctor suspects melanoma, he or she will first perform a skin biopsy, which means taking a tissue sample for examination by a pathologist. This can involve removing the entire mole or a portion of it. A diagnosis of melanoma can only be confirmed through analysis of the biopsy specimen.

Melanomas (left) versus normal moles (right)

Melanomas (left) versus normal moles (right)

There are several types of skin biopsies used to diagnose melanoma, including the punch, shave, and excisional biopsy. These involve removing several layers of skin, which are then sent to a laboratory and examined under a microscope. In an excisional biopsy, however, the physician removes the entire tumor.

The suspicious sample is prepared with a preservative solution (formalin) and then set into a wax block (paraffin). A portion of the tissue is then cut from the wax block, stained and reviewed under a microscope by a pathologist. This procedure is called histopathology. If the sample contains melanoma, the pathologist will then look for certain features like tumor thickness, mitotic rate (the portion of cells that are actively dividing), and ulceration status. These features can suggest whether the melanoma may have spread, which in turn affects your recommended treatment and prognosis.

Sentinel lymph node biopsy:
If your doctor suspects a high potential for metastasis

If melanoma is found on your skin and the features suggest a likelihood of metastasis, then the next step may be to have a biopsy of nearby (sentinel) lymph nodes to determine whether the cancer has spread through the body’s lymphatic system. This procedure is called a sentinel lymph node biopsy, often abbreviated as SLNB.

The sentinel lymph nodes are usually the first place the melanoma goes if it has metastasized, though it can also spread through the blood. To find the sentinel nodes, the surgeon injects a radioactive liquid or dye (or both) into the area of the melanoma and then checks to see which nodes are the first to drain fluid from the skin. Next, the surgeon determines which lymph nodes have absorbed radiation or turned blue and removes these nodes for examination by a pathologist under a microscope. If cancer cells are detected, the other lymph nodes in this area are removed as well. If the sentinel nodes do not contain cancer cells, however, the doctor typically will not perform further lymph node surgery.

There are other types of biopsies that may be used to detect metastasis. Fine needle aspiration biopsy, often abbreviated as FNAB, is performed if your doctor suspects the melanoma has spread to nearby lymph nodes or to organs such as the lungs or liver. In this procedure, a thin needle is used to remove a small sample of the tissue for further analysis.

In a surgical (excisional) lymph node biopsy, a lymph node is removed through a small cut in the skin. If the lymph node is deep within the body, you will need general anesthesia. This procedure is preferable if a lymph node is swollen enough to suggest that the cancer may have spread.

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