Melanoma is a form of skin cancer that begins in
melanocytes – the cells that make the brown pigment melanin.
Melanoma usually starts in a mole.
The skin is the body's largest organ. It protects
against heat, sunlight, injury, and infection. The skin has two main layers:
the epidermis (upper or outer layer) and
the dermis (lower or inner layer).
Melanocytes are found throughout the lower part of the epidermis. They make
melanin, the pigment that gives skin its natural color. When skin is exposed
to the sun, melanocytes make more pigment, causing the skin to tan, or darken.
When melanoma starts in the skin, the disease is called cutaneous melanoma.
Melanoma may also occur in the eye and is called intraocular or ocular melanoma.
Melanoma is the most aggressive of three types of skin cancer, the others
being basal cell skin cancer and squamous cell skin cancer.
Where on the body does melanoma occur?
Melanoma can occur anywhere on the body.
In men, melanoma is often found on the trunk (the area from the shoulders
to the hips) or the head and neck. In women, melanoma often develops on
the arms and legs. Melanoma usually occurs in adults, but it is sometimes
found in children and adolescents.
What increases the
risk of getting melanoma?
Unusual moles, exposure to sunlight, and health history can affect the risk
of developing melanoma.
Anything that increases your risk of getting a disease is called a risk
factor. Risk factors for melanoma include the following:
- Unusual moles
- Exposure to natural sunlight
- Exposure to artificial ultraviolet light (tanning booth)
- Family or personal history of melanoma
- Being white and older than 20 years
- Red or blond hair
- White or light-colored skin and freckles
- Blue eyes
What are the signs and symptoms of melanoma?
Possible signs of melanoma include a change in the appearance of a mole
or pigmented area.
|The ABCD rule for spotting a melanoma
These and other symptoms may be caused by melanoma or by other conditions.
A doctor should be consulted if any of the following problems occur:
Here is the "ABCD rule" to help tell a normal mole from a melanoma:
- A mole that:
- changes in size, shape, or color
- has irregular edges or borders
- is more than 1 color
- is asymmetrical (if the mole is divided in half, the 2 halves
are different in size or shape)
- oozes, bleeds, or is ulcerated (a hole forms in the skin when
the top layer of cells breaks down and the underlying tissue shows
- Change in pigmented (colored) skin.
- Satellite moles (new moles that grow near an existing mole).
Other important signs of melanoma include changes in size, shape, or color
of a mole. Some melanomas do not fit the descriptions above, and it may
be hard to tell if the mole is normal or not, so you should show your doctor
anything that you are unsure of.
- A: asymmetry – one half of the mole does not match the other half.
- B: border irregularity – the edges of the mole are ragged or notched.
- C: color – the color of the mole is not the same all over. There may
be shades of tan, brown, or black, and sometimes patches of red, blue,
- D: diameter – the mole is wider than about 1/4 inch (although doctors
are now finding more melanomas that are smaller).
How is melanoma diagnosed?
Tests that examine the skin are used to detect (find) and diagnose melanoma.
If a mole or pigmented area of the skin changes or looks abnormal, the following
tests and procedures can help detect and diagnose melanoma:
Suspicious areas should not be shaved off or cauterized (destroyed with
a hot instrument, an electrical current, or a caustic substance).
- Skin examination: A doctor or nurse examines the skin to look
for moles, birthmarks, or other pigmented areas that look abnormal in
color, size, shape, or texture.
- Biopsy: A local excision is
done to remove as much of the suspicious mole or lesion as possible.
A pathologist then looks at the tissue under a microscope to check for
cancer cells. Because melanoma can be hard to diagnose, patients should
consider having their biopsy sample checked by a second pathologist.
What affects the chance of recovery from melanoma?
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) and treatment options depend on the following:
Although many people are successfully treated, melanoma can recur (come
back). In recurrent melanoma, the cancer may come back at the original site
or in other parts of the body, such as the lungs or liver.
- The stage of melanoma (whether cancer is found in the outer layer
of skin only, or has spread to the lymph nodes, or to other places in
- Whether there was bleeding or ulceration at the primary site.
- The location and size of the tumor.
- The patient's general health.
What are the stages of melanoma?
In stage 0, melanoma is found only in the epidermis (outer layer of the
skin). Stage 0 is also called melanoma in situ.
Stage I is divided into stages IA and IB.
- Stage IA: In stage IA, the tumor is not more than 1 millimeter thick,
with no ulceration. The tumor is in the epidermis and upper layer of
- Stage IB: In stage IB, the tumor is either:
- not more than 1 millimeter thick, with ulceration, and may have
spread into the dermis or the tissues below the skin; or
- 1 to 2 millimeters thick, with no ulceration.
Stage II is divided into stages IIA, IIB, and IIC.
- Stage IIA: In stage IIA, the tumor is either:
- 1 to 2 millimeters thick, with ulceration; or
- 2 to 4 millimeters thick, with no ulceration.
- Stage IIB: In stage IIB, the tumor is either:
- 2 to 4 millimeters thick, with ulceration; or
- more than 4 millimeters thick, with no ulceration.
- Stage IIC: In stage IIC, the tumor is more than 4 millimeters thick,
In stage III, the tumor may be any thickness, with or without ulceration,
- has spread to 1 or more lymph nodes; or
- has spread into the nearby lymph system but not into nearby lymph
- has spread to lymph nodes that are matted (not moveable); or
- satellite tumors (additional tumor growths within 2 centimeters of
the original tumor) are present and nearby lymph nodes are involved.
In stage IV, the tumor may be any thickness, with or without ulceration,
may have spread to 1 or more nearby lymph nodes, and has spread to other
places in the body.
What tests are done to diagnose the
stage of melanoma?
The process used to find out whether cancer has spread within the skin or
to other parts of the body is called staging. The information gathered from
the staging process determines the stage of the disease. It is important
to know the stage in order to plan treatment.
The following tests and procedures may be used in the staging process:
The results of these tests are viewed together with the results of the tumor
biopsy to determine the melanoma stage.
- Wide local excision: A surgical procedure to remove some of the normal
tissue surrounding the area where melanoma was found, to check for cancer
- Lymph node mapping and sentinel
lymph node biopsy: Procedures in which a radioactive substance and/or
blue dye is injected near the tumor. The substance or dye flows through
lymph ducts to the sentinel node or nodes (the first lymph node or nodes
where cancer cells are likely to have spread). The surgeon removes only
the nodes with the radioactive substance or dye. A pathologist then
checks the sentinel lymph nodes for cancer cells. If no cancer cells
are detected, it may not be necessary to remove additional nodes.
- Chest X-ray: An X-ray of the organs
and bones inside the chest. An X-ray is a type of energy beam that can
go through the body and onto film, making a picture of areas inside
- CT scan (CAT
scan): A procedure that makes a series of detailed pictures of areas
inside the body, taken from different angles. The pictures are made
by a computer linked to an X-ray machine. A dye may be injected into
a vein or swallowed to help the organs or tissues show up more clearly.
This procedure is also called computed tomography, computerized tomography,
or computerized axial tomography. For melanoma, pictures may be taken
of the chest, abdomen, and pelvis.
- MRI (magnetic resonance
imaging): A procedure that uses a magnet, radio waves, and a computer
to make a series of detailed pictures of areas inside the body. This
procedure is also called nuclear magnetic resonance imaging (NMRI).
- PET scan (positron
emission tomography scan): A procedure to find malignant tumor cells
in the body. A small amount of radioactive glucose (sugar) is injected
into a vein. The PET scanner rotates around the body and makes a picture
of where glucose is being used in the body. Malignant tumor cells show
up brighter in the picture because they are more active and take up
more glucose than normal cells do.
- Laboratory tests: Medical procedures that test samples of tissue,
blood, urine, or other substances in the body. These tests help to diagnose
disease, plan and check treatment, or monitor the disease over time.
• HEALTH AND DISEASE
Source: National Cancer Institute