Melanoma or "black
mole cancer" is the name given to the most dangerous
form of skin cancer. The reason melanoma is so
dangerous is that once it grows to a certain
thickness, it metastasizes or spreads throughout the
body. After melanoma has spread to the internal
organs there is little that can be done and death
follows shortly after. This type of cancer tends to
occur in men and women in the prime of their lives.
Melanoma develops in the cells that produce
melanin (melanocytes) - the pigment that gives your
skin its color. It can also form in your eye
(intraocular melanoma) and in rare cases in internal
organs such as your intestine. But most melanomas
develop in your skin.
Although they make up the smallest percentage of
all skin cancers, melanomas cause the greatest
number of deaths. That's because they're more likely
than other skin cancers to spread to different parts
of your body (metastasize). The exact cause of all
melanomas isn't clear, but exposure to ultraviolet
(UV) radiation from sunlight or tanning lamps and
beds greatly increases the risk of developing the
Avoiding excessive sun exposure can prevent many
melanomas. And knowing the warning signs of
cancer can help ensure that malignant changes are
detected and treated before they can spread.
Melanoma can be successfully treated if it's caught
Signs and symptoms
Moles — the medical term is nevi — are clusters of pigmented
cells. Normal moles are generally a uniform color, such as tan, brown or
black, with a distinct border separating the mole from your surrounding
skin. They're oval or round in shape and average about one-quarter inch
(6 millimeters) in diameter — the size of a pencil eraser.
Most people have between 10 and 40 moles. Many of these develop by age
20 although they may change in appearance over time and some may even
disappear as you grow older.
Sometimes you may have one or more large (more than one-half inch, or 12
millimeters, in diameter), flat moles with irregular borders and a
mixture of colors, including tan, brown, and either red or pink. Known
medically as dysplastic nevi, these moles are much more likely to become
malignant than normal moles are.
In fact, the first sign of melanoma is often a change in an existing
mole or the development of a new, unusual-looking growth on your skin.
The American Academy of Dermatology has developed an ABCD guide for
determining when a mole is a matter for concern:
A is for
Symmetrical round or oval growths are usually noncancerous (benign).
Be alert for irregular shapes, where one half is different from the
B is for
Have your doctor check moles with notched, scalloped or vaguely
C is for color.
Look for growths that have many colors or an uneven distribution of
color. Growths that have the same overall color are usually benign.
D is for
Consult your doctor if you have any growths that are larger than
one-quarter inch (6 millimeters) — about the diameter of a pencil
Other suspicious changes in a mole may include:
Change in texture
— for instance, becoming hard or lumpy
pigment from the mole into the surrounding skin
Oozing or bleeding
Cancerous (malignant) moles vary greatly in appearance. Some may show
all of the changes listed above, while others may have only one or two
unusual characteristics. They can also develop on almost any part of
Some melanomas develop on skin that's frequently exposed to the sun such
as your face, lips, hands and arms. You can prevent these by wearing
sunscreen and protective clothing. But the majority of melanomas occur
in less exposed areas. In men they're often found on the back. Women
tend to develop melanomas on their lower legs.
Melanomas can also develop in the spaces between your toes and on your
palms, soles, scalp or genitals. These are sometimes referred to as
hidden melanomas because they occur in places most people wouldn't think
to check. Hidden melanomas include:
This rare form of melanoma occurs under a nail, most often on your
thumb or your big toe. It's especially common in blacks and in other
people with darker skin pigment. The first indication of a subungual
melanoma is usually a brown or black discoloration that's often
mistaken for a bruise (hematoma). See your dermatologist if you
develop a nail discoloration that increases in size or that doesn't
heal after 2 months.
This relatively uncommon type of melanoma develops in the mucosal
tissue that lines the nose, mouth, esophagus, anus, urinary tract
and vagina. Mucosal melanomas are especially hard to detect because
they can easily be mistaken for other, far more common conditions. A
melanoma that develops in your esophagus, for instance, causes pain
that's similar to a sore throat. A melanoma in a woman's genital
tract usually results in itching and bleeding — symptoms associated
with a yeast infection or menstrual irregularities. And symptoms of
anorectal melanoma are similar to those caused by hemorrhoids. Your
dentist is trained to spot melanomas that occur in your mouth, so
having regular dental checkups can help catch this type of cancer.
Having regular Pap tests can help spot melanomas in the vagina.
Symptoms of this type of melanoma, which may develop in the lining
of your eyelids (conjunctiva) or the pigmented coating within your
eyeball (choroid), include a scratchy feeling under your eyelid or a
dark spot in your vision. The number of white American men with
conjunctival melanoma have increased greatly over the past 30 years,
most likely as a result of sun exposure. This increase emphasizes
the importance of wearing dark glasses when you're spending time in
Most melanomas occur in more conspicuous places. The most common
spreading melanoma (SSM).
Approximately two-thirds of all melanomas are of this type. An SSM
usually first appears as a flat or slightly raised mark that's dark
with variegated colors and an irregular border. It occurs most often
on the legs in women and on the back and upper arms in men. It can
also occur on the soles or palms, especially in people of African or
Asian descent. Initially, an SSM spreads through the top layer of
skin (epidermis). If it's not caught and treated at this stage, it
eventually begins to grow into the underlying layers of skin — the
dermis and fatty layer — and may then spread to other parts of your
The most aggressive of all melanomas, NM usually appears as a small,
round bump (nodule) with a smooth border. Most NMs are black,
although some may be brown, blue, gray or even red in color. Because
this type of cancer spreads so rapidly, it's often quite advanced by
the time it's diagnosed.
Acral-lentiginous melanoma (ALM).
The most common skin cancer in people with deeper skin color, such
as blacks and Asians, ALM usually develops on the palms, soles or
nails. It's normally brown or black with irregular borders. Because
ALM is often mistaken for a minor problem, such as a bruise or
blister, it may have penetrated deep into the underlying layers of
skin before it's diagnosed.
The least threatening form of melanoma, LMM tends to develop on the
nose or cheeks of older adults. The lesions are flat and range in
size from 1.2 inches to 2.4 inches (3 centimeters to 6 centimeters)
or more. They tend to be tan, brown or black and generally don't
spread to other parts of the body. Instead, they're likely to spread
in the epidermis for months or even years before spreading to the
deeper layers of skin.
Sometimes people mistake seborrheic keratoses for skin cancer.
Seborrheic keratoses are waxy yellow, brown or black growths that look
as if they've been pasted on your skin. What causes them is unknown, but
they tend to occur in fair-skinned people older than 40. The growths
aren't cancerous, but you may want them removed for cosmetic reasons.