Melanoma Skin Cancer Overview

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Early Detection, Diagnosis, and Staging TOPICS

How is melanoma skin cancer found?

Melanoma can often be found early. There are things everyone can do to find this cancer early, when it is most likely to be cured.

Skin self-exams

It’s important to check your own skin about once a month. You should know the pattern of moles, freckles, and other marks on your skin so that you’ll notice any changes.

Skin self-exams are best done in front of a full-length mirror. A hand-held mirror can be used for places that are hard to see. Look at all areas, such as your palms and soles, scalp, ears, nails, and your back. A family member can check those hard-to-see areas like your scalp and back.

For a more on how to do a skin self-exam, see Skin Cancer Prevention and Early Detection, or visit our Skin Self-exam Image Gallery.

What to look for

Unusual moles, sores, lumps, blemishes, or changes in the way an area of the skin looks or feels may be a sign of melanoma or another type of skin cancer, or a warning that it might occur.

Normal moles

A normal mole is most often an evenly colored brown, tan, or black spot on the skin. It can be either flat or raised. It can be round or oval. Moles are usually less than 1/4 inch across, or about the width of a pencil eraser. Some moles can be present at birth, but most appear later.

Once a mole has developed, it most often stays the same size, shape, and color for many years. Some moles may fade away over time.

Most people have moles, and almost all moles are harmless. But it is important to notice changes in a mole that suggest a melanoma may be starting.

Possible signs and symptoms of melanoma

The most important warning sign for melanoma is a new spot on the skin or a spot that is changing in size, shape, or color. A spot that looks different from all of the other spots on your skin can also be a warning. If you have any of these warning signs, have your skin checked by a doctor. If you can’t see your doctor right away, you might want to take good close-up photos of the area so your doctor can see if the area is changing when you do get an appointment.

The ABCDE rule can help you tell if a mole should be checked by a doctor. ABCDE stands for the following:

  • A is for Asymmetry: One half of a mole or birthmark does not match the other.
  • B is for Border: The edges are irregular, ragged, notched, or blurred.
  • C is for Color: The color is not the same all over and may include shades of brown or black, or even pink, red, white, or blue.
  • D is for Diameter: The spot is larger than about ¼ inch across (the size of a pencil eraser), but melanomas can be smaller than this.
  • E is for Evolving: The mole is changing in size, shape, or color.

Some melanomas don’t fit the rules above. Other warning signs are:

  • A sore that does not heal
  • Spread of color from the border of a spot into the skin around it
  • Redness or a new swelling beyond the border
  • Itchiness, tenderness, or pain
  • Change in the surface of a mole – scaliness, oozing, bleeding, or a new bump or nodule

Be sure to show your doctor any areas that concern you and ask your doctor to look at areas that may be hard for you to see. It can be hard to tell the difference between melanoma and an ordinary mole, so it’s important to show your doctor any mole that you are unsure of.

To see some examples of normal moles and melanomas, visit our Skin Cancer Image Gallery.

Exam by a health professional

Part of a routine cancer check-up should include a skin exam by a doctor or trained health professional. Regular skin exams are especially important for people who have a higher risk of melanoma, such as people with a strong family history or who have had melanoma before.

If there is any reason to suspect that you have a melanoma, your doctor will do more exams and tests to find out if it is melanoma or something else. You might also be referred to a doctor who is an expert in skin diseases (called a dermatologist) for some of these tests.

Medical history and physical exam

The doctor will likely ask about your symptoms and risk factors. This will include when you first saw the mark on your skin, if it has changed in size or the way it looks, and if it is causing any symptoms (pain, itching, bleeding, etc.).

During the exam, the doctor will note the size, shape, color, and texture of the area of concern, and whether it is bleeding or oozing. The rest of your body may be checked for moles and other spots. The doctor may also feel nearby lymph nodes under the skin, like those in the groin, underarm, or neck. If the lymph nodes are enlarged, it might mean the melanoma has spread.

The doctor might use a special magnifying lens and light source held near the skin. Sometimes a thin layer of oil is put on the skin. A picture of the spot may be taken.

Skin biopsy

If the doctor thinks a spot might be a melanoma, a sample of the skin will be taken and sent to a lab to be looked at with a microscope. This is called a biopsy. There are different ways to biopsy the skin. The choice depends on the size of the area of concern and where it is on the body.

The skin around the area of the biopsy will be numbed before the biopsy. You will feel a little stinging as the medicine goes in, but you should not feel any pain during the biopsy.

Shave biopsy: For this type of biopsy, the doctor shaves off the top layers of the skin. Bleeding from the biopsy site is then stopped by applying an ointment, a chemical that stops bleeding, or a small electric current to cauterize the wound.

A shave biopsy is useful for sampling moles when the risk of melanoma is very low. But it is not usually done if the doctor strongly suspects melanoma unless the biopsy blade goes deep enough to get below the area in question.

Punch biopsy: In a punch biopsy, the doctor uses a tool that looks like a tiny round cookie cutter to remove a deeper sample of skin. The edges of the skin are often stitched together.

Incisional and excisional biopsies: If a tumor might have grown into deeper layers of the skin, an incisional or excisional biopsy will be done. A surgical knife is used to cut through the full thickness of skin. A wedge of skin is removed, and the edges of the cut are usually sewn together.

An incisional biopsy removes only part of the tumor. If the whole tumor is removed, it is called an excisional biopsy. Excisional biopsy is most often used when it can be done.

Biopsies of melanoma that might have spread

If melanoma has already been found on the skin, nearby lymph nodes or other areas may be biopsied to see if the cancer has spread.

Rarely, some melanomas spread so fast that a person could have cancer in the lymph nodes, lungs, brain, or other places before a spot on the skin is found. In other cases they may be found long after a skin melanoma has been removed, so it’s not clear whether it is the same cancer. Melanoma can also start in internal organs, but this is very rare.

Melanoma in an internal organ might be confused with another type of cancer starting in that organ. For example, melanoma that has spread to the lung might be confused with a cancer that starts in the lung. Special tests can be done on biopsy samples to tell whether it is a melanoma or some other kind of cancer. This is important because different treatments are used for different cancers.

Fine needle aspiration biopsy (FNA): This kind of biopsy is not used on suspicious moles, but it can sometimes be used if the doctor thinks the melanoma has spread to nearby lymph nodes or to organs like the lung or liver. A thin, hollow needle is used to remove very small tissue samples from the tumor. The test rarely causes much discomfort and does not leave a scar. But it may not always collect enough of a sample to tell if melanoma is present.

Surgical (excisional) lymph node biopsy: For this type of biopsy a swollen lymph node is removed through a small cut (incision). It is often done if a lymph node’s size suggests the melanoma has spread there but either an FNA was not done or it did not show any cancer cells. Numbing medicine is often put on the skin if the lymph node is near the surface of the body. But if the lymph node is deeper in the body, you may need to be made drowsy or even put into a deep sleep (using general anesthesia).

Sentinel lymph node biopsy: If melanoma has been diagnosed and has any concerning features (such as being at least a certain thickness), a sentinel lymph node biopsy is often done to find out if the cancer has spread to nearby lymph nodes. This test can find the lymph nodes that drain lymph fluid from the area of the skin where the melanoma started. These sentinel lymph nodes are likely to be the first place the melanoma would go if it spreads.

To find the sentinel lymph nodes, the doctor injects a radioactive liquid (and sometimes a blue dye) into the area of the melanoma. The lymph nodes are then checked for radioactivity. A small cut is made in the identified lymph node area. The lymph nodes are then checked to find which one(s) absorbed radiation and turned blue. When these lymph nodes are found, they are taken out and sent to a lab to be looked at with a microscope. If cancer cells are found, the rest of the lymph nodes in this area are removed, too. If the sentinel nodes do not contain cancer cells, further lymph node surgery is not needed.

If a lymph node near a melanoma is very large, this test probably won’t be needed. The enlarged node is simply biopsied.

Lab tests of biopsy samples

After a biopsy, the samples are sent to a lab to be looked at with a microscope. If the doctor can’t tell for sure if the sample contains melanoma cells just by looking at it, special tests may be done on the cells to try to confirm the diagnosis.

If the samples do contain melanoma, the doctor will look at certain features such as the tumor thickness and the portion of cells that are actively dividing. These features help define the stage of the melanoma (see the section “How is melanoma of the skin staged?”), which in turn affects treatment options and the outlook (prognosis) for the patient.

Tests may be done on advanced melanomas to see if the cancer cells have changes in genes such as the BRAF gene. This could help decide which treatments might work. (See the section “Targeted therapy for melanoma skin cancer.”)

Imaging tests

Imaging tests are done to create pictures of the inside of the body. They are used to look for the spread of melanoma. They are not needed for people with very early melanoma, which is not likely to have spread. These tests may also be done to help find out how well treatment is working or to look for signs that the cancer has come back after treatment.

Chest x-ray: This test may be done to see if the cancer has spread to the lungs.

CT (computed tomography) scan: A CT scan uses x-rays to make detailed pictures of the inside of your body. This test can help show if any lymph nodes are enlarged or if organs such as the lungs or liver have spots that might be from the spread of melanoma.

CT scans can also be used to guide a needle during a biopsy. For this, you stay on the CT scanning table while a biopsy needle is moved through the skin and toward the mass.

MRI (magnetic resonance imaging): This is like a CT scan except that it uses radio waves and strong magnets to make a picture of your insides. MRI scans are very helpful in looking at the brain and spinal cord.

PET (positron emission tomography) scan: In this test, a special kind of radioactive sugar is put into a vein. The sugar collects in areas that have cancer, and a scanner can spot these areas. This test can be useful to see if the cancer has spread to lymph nodes or other parts of the body. It can also help when the doctor thinks the cancer has spread but doesn’t know where. Doctors find it most useful in people with advanced stages of melanoma. Some newer machines do PET scans and CT scans at the same time.

To learn more about these imaging tests, see Imaging (Radiology) Tests.

Blood tests

Blood tests aren’t used to find melanoma, but some tests may be done before or during treatment, especially for more advanced melanomas.

Doctors often test blood for lactate dehydrogenase (LDH) before treatment. If the melanoma has spread to distant parts of the body, a higher than normal level of LDH is a sign that the cancer may be harder to treat. This affects how the cancer is staged.

Some other tests of blood cell counts and blood chemistry levels may be done in a person who has advanced melanoma to see how well the bone marrow (where new blood cells are made), liver, and kidneys are working during treatment.

Last Medical Review: 05/01/2015
Last Revised: 05/18/2015