A member of the Seattle Cancer Care Alliance Network

Melanoma Skin Cancer Diagnosis

Melanoma usually appears as a change in a mole or other skin growth, such as a birthmark. It can also appear as a change in the skin where there’s never been a mole or growth before. A patient can discover the skin change, or it can be found during a routine exam.

Melanomas typically look and feel different than other skin growths. The edges are often irregular and not symmetrical (same on all sides). They might be skin-colored, pink, red, blue, white, brown, black — or a mixture of colors.

Check with your doctor if you have a growth, mole, or other skin mark that:

  • Changes in color, size, or shape.
  • Starts to look lumpy or more rounded.
  • Starts to ooze, get crusty, bleed, or itch. 

Picture of the ABCDEs of melanoma

The ABCDEs of melanoma skin cancer are:

  • Asymmetry: One half doesn't match the appearance of the other half.
  • Border irregularity: The edges are ragged, notched, or blurred.
  • Color. The color (pigmentation) is not uniform. Shades of tan, brown, and black are present. Dashes of red, white, and blue add to a mottled appearance.
  • Diameter. The size of the mole is greater than 1/4 inch, about the size of a pencil eraser. Any growth of a mole should be evaluated.
  • Evolution. There is a change in the size, shape, symptoms (such as itching or tenderness), surface (especially bleeding), or color of a mole.

Diagnostic Tests

Sometimes a dermatologist (specialist in skin conditions) can find a growth that looks like melanoma during a skin exam. A biopsy, a procedure that examines a sample of your skin, is often the only way to know for certain if it is skin cancer, and what type of cancer it is.

In a biopsy, your personal physician, dermatologist, physician assistant, or nurse practitioner will remove all or part of a mole or skin growth. You will have a shot to numb your skin and then have the biopsy, which will do one of the following:

  • Shave off the top layer of skin (not usually used if testing for melanoma)
  • Take a deeper sample of tissue using a punch, which looks like a tiny round cookie cutter
  • Remove a wedge or the whole tumor (incisional and excisional biopsy)

After your biopsy, a pathologist will test the sample for cancer cells. Your doctor will let you know the results of the biopsy, which usually takes up to a week to be completed.

Stages of Melanoma

If you are diagnosed with melanoma, the doctors may do more tests to find out the stage of the cancer. Staging tests will measure the extent of the cancer, if it has spread, and the following features of the growth:

  • How thick the melanoma is, including what's below the surface of the skin.
  • Whether the top layer (epidermis) of the melanoma is smooth and unbroken.
  • Whether cancer has spread to lymph nodes close to the melanoma, through a lymph-node biopsy. Lymph is a fluid that carries cells that help fight infection. Usually if cancer hasn’t spread to the lymph nodes it means it hasn’t spread to other parts of the body.

The stages of melanoma range from Stage 0 to Stage 4.

Stage 0

  • The melanoma tumor does not break through the surface of the skin (melanoma in situ).

Stage 1

  • The melanoma tumor is up to 2 millimeters (mm) — a little more than the thickness of a quarter. Cancer hasn’t spread to the nearby lymph nodes.

Stage 2

  • The melanoma tumor is up to 4 mm (about the thickness of 2 quarters). Cancer has not spread to nearby lymph nodes.

Stage 3

  • Melanoma has started to spread (metastasize) to the skin near the melanoma and to nearby lymph nodes and/or lymph channels.

Stage 4

  • Melanoma has started to spread to distant sites in the body or to distant areas of the skin.

After determining the stage of the cancer, your doctor will be able to recommend a treatment plan for you.

Our doctors and cancer care team at Kaiser Permanente medical offices can answer any questions you have during testing and diagnosis.