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Melanoma Diagnosis

Early and accurate diagnosis is important in melanoma care. This helps find out if the cancer has spread and helps your doctor choose the most effective treatment.

MD Anderson has the most modern and accurate technology to diagnose melanoma and find out if it has spread. This helps increase the likelihood that your treatment will be successful. Our staff includes pathologists and diagnostic radiologists who are highly skilled in diagnosing melanoma.

Diagnostic Tests

If you have signs or symptoms that may signal melanoma, your doctor will examine you and ask you questions about your health, your lifestyle and your family history. If your doctor suspects a spot may be melanoma, a biopsy will be done.


Skin cancer can't be diagnosed just by looking at it. If a mole or pigmented area of the skin changes or looks abnormal, your doctor may biopsy the mark, taking a tissue sample for a pathologist to examine. Suspicious areas should not simply be shaved off or cauterized (destroyed with a hot instrument, an electrical current or a caustic substance). A biopsy should be performed first to determine if the area is malignant.

Your doctor may use one of these biopsy methods:

Local excision/excisional biopsy: The entire suspicious area is removed with a scalpel under local anesthetic. Depending on the size and location of the suspicious area, this type of biopsy may be done in a doctor's office or as an outpatient procedure at a hospital. Your doctor will put in stitches to close the excision and cover the area with a bandage.

Punch biopsy: The doctor uses a tool to punch through the suspicious area and remove a round cylinder of tissue.

Shave biopsy: The doctor shaves off a piece of the growth.

The sample of skin is sent to a pathologist, who looks at it under a microscope to check for cancer cells. Your tissue may be judged normal or abnormal. Abnormal results may include:

  • Benign (non-cancerous) growths such as moles, warts and benign skin tumors
  • Squamous cell carcinoma (cancer)
  • Basal cell carcinoma
  • Melanoma

Because melanoma can be hard to diagnose, you should consider having your biopsy checked by a second pathologist.

Side Effects

As with any time the skin is cut, there is a small risk of infection after a biopsy. You should call your doctor if you have a fever, an increase in pain, reddening or swelling at the infection site, or continued bleeding.

If your skin usually scars when injured, the biopsy may leave a scar. For this reason, a biopsy on the face might be better performed by a surgeon or dermatologist who specializes in methods that reduce scarring.

Before you have a skin biopsy, you should tell your doctor what medications you are taking, including anti-inflammatory medication, which may make your biopsy look different to the pathologist, or blood thinners like Coumadin or aspirin, which could cause bleeding problems.

Other Tests

After melanoma has been diagnosed, tests may be recommended to find out if cancer cells have spread within the skin or to other parts of the body. These may include:

Imaging tests, such as:

  • Chest X-ray
  • Lymphoscintigraphy
  • Ultrasound
  • CT or CAT (computed axial tomography) scans
  • MRI (magnetic resonance imaging) scans
  • PET (positron emission tomography) scans

Visit the Prevention section of our website to find out steps you can take to avoid cancer.

Melanoma Staging

If you are diagnosed with melanoma, your doctor will determine the stage (or extent) of the disease. Staging is a way of determining how much disease is in the body and where it has spread. This information is important because it helps your doctor determine the best type of treatment for you and the outlook for your recovery (prognosis).  

Melanoma staging is based on:

  • Location(s) of the melanoma
  • Primary melanoma tumor thickness as well as other microscopic features
  • If it has spread to nearby lymph nodes – if so, how many and what size
  • If it has spread (metastasized) to other parts of the body
  • A blood test called lactate dehydrogenase (LDH) for stage IV melanoma

Stages I and II are based mainly on the thickness of the primary melanoma and other microscopic features. Stages III and IV are based on how far the melanoma has spread from the skin; stage III signifies regional spread and stage IV is based on distant spread

Melanoma Stages

Stage 0 (Melanoma in situ):

  • Does not reach below the surface of the skin
  • Tumor thickness is not recorded for melanoma in situ

Stage IA: Melanoma:

  • Is less than 1 millimeter thick
  • Without ulceration
  • Has less than 1 mitosis (dividing cell) per square millimeter

Stage IB: Melanoma:

  • Is less than 1 millimeter thick and with ulceration and/or has at least 1 mitosis (dividing cell) per square millimeter or
  • 1 to 2 millimeters thick without ulceration

Stage IIA: Melanoma is either:

  • 1 to 2 millimeters thick with ulceration or
  • 2 to 4 millimeters thick with no ulceration

Stage IIB: Melanoma is either:

  • 2 to 4 millimeters thick with ulceration or
  • More than 4 millimeters thick without ulceration

Stage IIC: Melanoma is more than 4 millimeters thick with ulceration

Stage III: Melanoma:

  • Has spread through the lymph system (eg, satellites and/or in-transit metastasis) or directly into the regional lymph nodes (ie, lymph nodes that receive lymph drainage from primary tumor site)
  • Has not spread to distant organs

Stage IV: Melanoma has spread (metastasized) to more distant lymph nodes and/or to other distant organs.

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Knowledge Center

Find the latest news and information about melanoma in our Knowledge Center, including blog posts, articles, videos, news releases and more.