Diagnosing Melanoma

At Virginia Mason's Melanoma Program, in Seattle, a dedicated treatment team may include dermatologists, surgeons, medical oncologists, radiation oncologists, pathologists, radiologists, nurses and social workers.

Diagnosing Melanoma

A definitive diagnosis of melanoma is made with an excisional biopsy that removes the mole and a margin of tissue surrounding it, or with a "punch" biopsy of the thickest part of the mole if it is large or in a difficult anatomical area to reach. These biopsies are outpatient procedures performed in your doctor's office. A pathologist will look at the sample under a microscope and determine if the cells are cancerous. The biopsy sample, along with other tests and procedures, allows the pathologist to determine the stage of disease, upon which treatment decisions are then made.

Excisional Biopsy

An excisional biopsy removes the mole and a margin of tissue surrounding it. Because melanomas can grow deep into the skin layer, your surgeon may remove tissue down to the subcutaneous layer — the lowermost portion — of skin. First, the area will be numbed with a local anesthetic. Your doctor will remove the mole and a margin of tissue and send this biopsy sample to a pathologist. The surgical area will be sewn closed. The procedure may take 30 minutes or less.

Punch Biopsy

During a punch biopsy your doctor will take a core sample of the mole, preferably in its thickest part. Your doctor will numb the area first with a local anesthetic. The biopsy will be taken with a small tool that punches through the mole to an ascertained depth and removes the sample. The area is closed with stitches and the sample is sent to pathology for review.

Staging of Melanoma

Staging is a method clinicians use to categorize melanomas for the purpose of evaluation, treatment and prognosis. Virginia Mason uses the staging system developed by the American Joint Commission on Cancer (AJCC) that assigns categories based on tumor (T), lymph node (N) and metastatic (M) status. Melanomas are also assigned an anatomic level or "Clark's level" I to IV as a description of tumor depth into the skin.

In addition, staging of cancer may include the following descriptions:

  • Stage I and stage II: Melanoma is confined to the site where the cancer occurred and has not spread to the lymph nodes or internal organs.
  • Stage III: Melanoma has spread to the lymph nodes.
  • Stage IV: Melanoma has spread to distant organs (metastasis).

Additional Tests and Procedures

You may also have any one or more of the following tests and procedures to determine if cancer has spread:

  • Chest X-ray — A simple chest X-ray may show lesions (growths) in the lungs.
  • Lab tests — You may have blood and urine tests to determine if cancer "markers" are present in your blood or urine. Markers are substances such as hormones or proteins made by your body in response to cancer or made by the tumor itself. These tests are also used to monitor treatment as well as disease status.
  • Sentinel lymph node biopsy — During this procedure, the first (sentinel) node or nodes near the tumor site are removed and tested for cancer cells. Prior to the procedure, patients have an injection that flows through the lymphatic system near the tumor. The surgeon removes only the lymph nodes that are identified with this mapping, which are the first nodes where cancer may have spread. If cancer is not detected by a pathologist, usually no additional lymph nodes are removed.
  • CT scan (CAT scan) — A CT scan - essentially a computer and X-ray machine - provides three-dimensional images of tissues and organs within the body. For patients with melanoma, images may be taken of the chest, abdomen and pelvis. In some instances a dye is injected first to enhance the images.
  • Magnetic resonance imaging (MRI) — An MRI uses a magnet, radio waves, and a computer to create detailed pictures of areas within the body.
  • CT/PET scan (positron emission tomography scan) — A PET scan shows areas in the body that are "taking up" sugar. These areas appear as "hot spots" on the PET scan because cancer cells use sugar at a faster rate than normal cells do.

For more information or to schedule a consultation with a melanoma specialist, call (206) 223-6831.