Not all moles are cancerous. It is estimated that nearly four to five out of every 100 Caucasians will develop at least one skin cancer by the time they are 65 years old.
If you have a mole, you need to keep checking if it changes over time. The signs of a mole being cancerous include:
- Asymmetry: A normal (or a common) mole is symmetrical, whereas a cancerous mole looks asymmetrical. That means if the cancerous mole is divided into two equal portions by drawing a line in the middle of it, the halves will be unequal.
- Irregular border: A normal mole will have a smooth, even or regular border. A cancerous mole will have edges that look ragged, notched or blurred.
- Uneven color: A normal mole will have a single shade of brown that is evenly distributed throughout. A cancerous mole will have shades or hues of black and brown. In between, areas of red, pink, white, gray or blue may also be seen.
- Diameter: The size or diameter of a normal mole will remain constant throughout life. If a mole is cancerous, then it will grow in size. A cancerous mole is often larger than the size of a pea (larger than 6 mm or about 1/4 inch).
- Evolving: Any change in the mole over the past few weeks or months needs to be evaluated. Look for the change in size, shape, color or elevation of the mole on the skin. Any other sign, such as bleeding, itching, burning sensation or crusting, may indicate the development of cancerous changes in the mole.
How does a doctor confirm that a mole has become cancerous?
Diagnosis of a cancerous mole
- Take the detailed medical history. They will ask about the appearance of the mole (gradual or sudden), any associated symptoms and history of skin cancer in the family.
- Examine the skin. This is the first step in the diagnosis of melanoma. The doctor will examine the skin by observing it. They may use a magnifying lens.
- Perform a skin biopsy. A skin biopsy is a procedure that involves removing a small portion of the cancerous mole and sending it to the laboratory. In the laboratory, the sample of the mole is observed under a microscope to look for changes that may indicate melanoma. This test provides a definitive diagnosis of melanoma and other types of skin cancer.
Determining the extent of the cancer
After the doctor diagnoses melanoma, the next step is to find out how far the cancer has spread. The doctor will
- Determine the thickness of the melanoma. To see how thick the melanoma is, the doctor will look at it under a microscope and use a special tool to determine its thickness. The thicker the melanoma, the more serious it is.
- Check if the melanoma has spread to the lymph nodes. To find out if the melanoma has spread to the lymph nodes, the doctor will perform a sentinel node biopsy. This procedure involves injecting a special dye into the lymph nodes. The lymph nodes that absorb the dye first are tested for cancerous cells.
- Check if the melanoma has spread to other organs. If the doctor suspects that melanoma has spread beyond the skin, they may order additional tests that include X-rays, computed tomography (CT) and positron emission tomography (PET) scans.
Once all the above factors have been determined, the doctor will stage the melanoma from stage I to IV. The higher the stage, the more serious is the cancer. Staging melanoma helps the doctor decide the right treatment approaches.