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Diseases and Conditions
Skin cancer
By Mayo Clinic Staff
Skin cancer — the abnormal growth of skin cells — most often develops on skin exposed to the
sun. But this common form of cancer can also occur on areas of your skin not ordinarily
exposed to sunlight.
There are three major types of skin cancer — basal cell carcinoma, squamous cell carcinoma
and melanoma.
You can reduce your risk of skin cancer by limiting or avoiding exposure to ultraviolet (UV)
radiation. Checking your skin for suspicious changes can help detect skin cancer at its earliest
stages. Early detection of skin cancer gives you the greatest chance for successful skin cancer
treatment.
Where skin cancer develops
Skin cancer develops primarily on areas of sun-exposed skin, including the scalp, face, lips,
ears, neck, chest, arms and hands, and on the legs in women. But it can also form on areas that
rarely see the light of day — your palms, beneath your fingernails or toenails, and your genital
area.
Skin cancer affects people of all skin tones, including those with darker complexions. When
melanoma occurs in people with dark skin tones, it's more likely to occur in areas not normally
exposed to the sun.
Basal cell carcinoma signs and symptoms
Basal cell carcinoma usually occurs in sun-exposed areas of your body, such as your neck or
face.
Basal cell carcinoma may appear as:
A pearly or waxy bump
A flat, flesh-colored or brown scar-like lesion
Squamous cell carcinoma signs and symptoms
Most often, squamous cell carcinoma occurs on sun-exposed areas of your body, such as your
face, ears and hands. People with darker skin are more likely to develop squamous cell
carcinoma on areas that aren't often exposed to the sun.
Squamous cell carcinoma may appear as:
A firm, red nodule
A flat lesion with a scaly, crusted surface
Melanoma signs and symptoms
Melanoma can develop anywhere on your body, in otherwise normal skin or in an existing mole
that becomes cancerous. Melanoma most often appears on the face or the trunk of affected
men. In women, this type of cancer most often develops on the lower legs. In both men and
women, melanoma can occur on skin that hasn't been exposed to the sun.
Melanoma can affect people of any skin tone. In people with darker skin tones, melanoma
tends to occur on the palms or soles, or under the fingernails or toenails.
Melanoma signs include:
A large brownish spot with darker speckles
A mole that changes in color, size or feel or that bleeds
A small lesion with an irregular border and portions that appear red, white, blue or blueblack
Dark lesions on your palms, soles, fingertips or toes, or on mucous membranes lining your
mouth, nose, vagina or anus
Signs and symptoms of less common skin cancers
Other, less common types of skin cancer include:
Kaposi sarcoma. This rare form of skin cancer develops in the skin's blood vessels and
causes red or purple patches on the skin or mucous membranes.
Kaposi sarcoma mainly occurs in people with weakened immune systems, such as people
with AIDS, and in people taking medications that suppress their natural immunity, such as
people who've undergone organ transplants.
Other people with an increased risk of Kaposi sarcoma include young men living in Africa
or older men of Italian or Eastern European Jewish heritage.
Merkel cell carcinoma. Merkel cell carcinoma causes firm, shiny nodules that occur on or
just beneath the skin and in hair follicles. Merkel cell carcinoma is most often found on the
head, neck and trunk.
Sebaceous gland carcinoma. This uncommon and aggressive cancer originates in the
oil glands in the skin. Sebaceous gland carcinomas — which usually appear as hard,
painless nodules — can develop anywhere, but most occur on the eyelid, where they're
frequently mistaken for other eyelid problems.
When to see a doctor
Make an appointment with your doctor if you notice any changes to your skin that worry you. Not
all skin changes are caused by skin cancer. Your doctor will investigate your skin changes to
determine a cause.
Skin cancer occurs when errors (mutations) occur in the DNA of skin cells. The mutations
cause the cells to grow out of control and form a mass of cancer cells.
Cells involved in skin cancer
Skin cancer begins in your skin's top layer — the epidermis. The epidermis is a thin layer that
provides a protective cover of skin cells that your body continually sheds. The epidermis
contains three main types of cells:
Squamous cells lie just below the outer surface and function as the skin's inner lining.
Basal cells, which produce new skin cells, sit beneath the squamous cells.
Melanocytes — which produce melanin, the pigment that gives skin its normal color — are
located in the lower part of your epidermis. Melanocytes produce more melanin when you're
in the sun to help protect the deeper layers of your skin.
Where your skin cancer begins determines its type and your treatment options.
Ultraviolet light and other potential causes
Much of the damage to DNA in skin cells results from ultraviolet (UV) radiation found in sunlight
and in the lights used in tanning beds. But sun exposure doesn't explain skin cancers that
develop on skin not ordinarily exposed to sunlight. This indicates that other factors may
contribute to your risk of skin cancer, such as being exposed to toxic substances or having a
condition that weakens your immune system.
Factors that may increase your risk of skin cancer include:
Fair skin. Anyone, regardless of skin color, can get skin cancer. However, having less
pigment (melanin) in your skin provides less protection from damaging UV radiation. If you
have blond or red hair and light-colored eyes, and you freckle or sunburn easily, you're much
more likely to develop skin cancer than is a person with darker skin.
A history of sunburns. Having had one or more blistering sunburns as a child or teenager
increases your risk of developing skin cancer as an adult. Sunburns in adulthood also are a
risk factor.
Excessive sun exposure. Anyone who spends considerable time in the sun may develop
skin cancer, especially if the skin isn't protected by sunscreen or clothing. Tanning, including
exposure to tanning lamps and beds, also puts you at risk. A tan is your skin's injury
response to excessive UV radiation.
Sunny or high-altitude climates. People who live in sunny, warm climates are exposed to
more sunlight than are people who live in colder climates. Living at higher elevations, where
the sunlight is strongest, also exposes you to more radiation.
Moles. People who have many moles or abnormal moles called dysplastic nevi are at
increased risk of skin cancer. These abnormal moles — which look irregular and are
generally larger than normal moles — are more likely than others to become cancerous. If
you have a history of abnormal moles, watch them regularly for changes.
Precancerous skin lesions. Having skin lesions known as actinic keratoses can increase
your risk of developing skin cancer. These precancerous skin growths typically appear as
rough, scaly patches that range in color from brown to dark pink. They're most common on
the face, head and hands of fair-skinned people whose skin has been sun damaged.
A family history of skin cancer. If one of your parents or a sibling has had skin cancer,
you may have an increased risk of the disease.
A personal history of skin cancer. If you developed skin cancer once, you're at risk of
developing it again.
A weakened immune system. People with weakened immune systems have a greater
risk of developing skin cancer. This includes people living with HIV/AIDS and those taking
immunosuppressant drugs after an organ transplant.
Exposure to radiation. People who received radiation treatment for skin conditions such
as eczema and acne may have an increased risk of skin cancer, particularly basal cell
carcinoma.
Exposure to certain substances. Exposure to certain substances, such as arsenic, may
increase your risk of skin cancer.
Make an appointment with your family doctor or a general practitioner if you notice any unusual
skin changes that worry you. In some cases, you may be referred to a doctor who specializes in
skin diseases and conditions (dermatologist).
Because appointments can be brief, and because there's often a lot of ground to cover, it's a
good idea to be well prepared. Here's some information to help you get ready, and know what
to expect from your doctor.
What you can do
Be aware of any pre-appointment restrictions. At the time you make the appointment,
be sure to ask if there's anything you need to do in advance, such as restrict your diet.
Write down any symptoms you're experiencing, including any that may seem unrelated
to the reason for which you scheduled the appointment.
Write down key personal information, including any major stresses or recent life
changes.
Make a list of all medications, vitamins or supplements that you're taking.
Consider taking a family member or friend along. Sometimes it can be difficult to
remember all the information provided during an appointment. Someone who accompanies
you may remember something that you missed or forgot.
Write down questions to ask your doctor.
Your time with your doctor is limited, so preparing a list of questions can help you make the
most of your time together. List your questions from most important to least important in case
time runs out. For skin cancer, some basic questions to ask your doctor include:
Do I have skin cancer?
What type of skin cancer do I have?
Will I need additional tests?
What are my treatment options?
What are the potential risks of each treatment?
Will surgery leave a scar?
Do I have an increased risk of additional skin cancers?
How can I reduce my risk of additional skin cancers?
Should I have regular skin exams to check for additional skin cancers?
Should I see a specialist? What will that cost, and will my insurance cover it?
Is there a generic alternative to the medicine you're prescribing me?
Are there brochures or other printed material that I can take with me? What websites do you
recommend?
What will determine whether I should plan for a follow-up visit?
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask other
questions that occur to you.
What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may allow
time to cover other points you want to address. Your doctor may ask:
When did you first begin experiencing symptoms?
Have your symptoms been continuous or occasional?
How severe are your symptoms?
What, if anything, seems to improve your symptoms?
What, if anything, appears to worsen your symptoms?
Diagnosing skin cancer
To diagnose skin cancer, your doctor may:
Examine your skin. Your doctor may look at your skin to determine whether your skin
changes are likely to be skin cancer. Further testing may be needed to confirm that
diagnosis.
Remove a sample of suspicious skin for testing (skin biopsy). Your doctor may
remove a small sample of suspicious-looking skin for laboratory testing. A biopsy can
determine whether you have skin cancer and, if so, what type of skin cancer you have.
Determining the extent of the skin cancer
If your doctor determines you have skin cancer, you may have additional tests to determine the
extent (stage) of the skin cancer.
Because superficial skin cancers such as basal cell carcinoma rarely spread, a biopsy which
removes the entire growth often is the only test needed to determine the cancer stage. But if
you have a large squamous cell carcinoma, Merkel cell carcinoma or melanoma, your doctor
may recommend further tests to determine the extent of the cancer.
Doctors use the Roman numerals I through IV to indicate a cancer's stage. Stage I cancers are
small and limited to the area where they began. Stage IV indicates advanced cancer that has
spread to other areas of the body.
The skin cancer's stage helps determine which treatment options will be most effective.
Your treatment options for skin cancer and the precancerous skin lesions known as actinic
keratoses will vary, depending on the size, type, depth and location of the lesions. Small skin
cancers limited to the surface of the skin may not require treatment beyond an initial skin
biopsy that removes the entire growth.
If additional treatment is needed, options may include:
Freezing. Your doctor may destroy actinic keratoses and some small, early skin cancers by
freezing them with liquid nitrogen (cryosurgery). The dead tissue sloughs off when it thaws.
Excisional surgery. This type of treatment may be appropriate for any type of skin cancer.
Your doctor cuts out (excises) the cancerous tissue and a surrounding margin of healthy
skin. A wide excision — removing extra normal skin around the tumor — may be
recommended in some cases.
Mohs surgery. This procedure is for larger, recurring or difficult-to-treat skin cancers,
which may include both basal and squamous cell carcinomas. It's often used in areas where
it's necessary to conserve as much skin as possible, such as on the nose.
During Mohs surgery, your doctor removes the skin growth layer by layer, examining each
layer under the microscope, until no abnormal cells remain. This procedure allows
cancerous cells to be removed without taking an excessive amount of surrounding healthy
skin.
Curettage and electrodesiccation or cryotherapy. After removing most of a growth,
your doctor scrapes away layers of cancer cells using a device with a circular blade (curet).
An electric needle destroys any remaining cancer cells. In a variation of this procedure,
liquid nitrogen can be used to freeze the base and edges of the treated area.
These simple, quick procedures may be used to treat basal cell cancers or thin squamous
cell cancers.
Radiation therapy. Radiation therapy uses high-powered energy beams, such as X-rays,
to kill cancer cells. Radiation therapy may be an option when cancer can't be completely
removed during surgery.
Chemotherapy.In chemotherapy, drugs are used to kill cancer cells. For cancers limited to
the top layer of skin, creams or lotions containing anti-cancer agents may be applied
directly to the skin. Systemic chemotherapy can be used to treat skin cancers that have
spread to other parts of the body.
Photodynamic therapy. This treatment destroys skin cancer cells with a combination of
laser light and drugs that makes cancer cells sensitive to light.
Biological therapy. Biological treatments stimulate your immune system in order to kill
cancer cells.
Most skin cancers are preventable. To protect yourself, follow these skin cancer prevention tips:
Avoid the sun during the middle of the day. For many people in North America, the
sun's rays are strongest between about 10 a.m. and 4 p.m. Schedule outdoor activities for
other times of the day, even in winter or when the sky is cloudy.
You absorb UV radiation year-round, and clouds offer little protection from damaging rays.
Avoiding the sun at its strongest helps you avoid the sunburns and suntans that cause skin
damage and increase your risk of developing skin cancer. Sun exposure accumulated over
time also may cause skin cancer.
Wear sunscreen year-round. Sunscreens don't filter out all harmful UV radiation,
especially the radiation that can lead to melanoma. But they play a major role in an overall
sun protection program.
Use a broad-spectrum sunscreen with an SPF of at least 15. Apply sunscreen generously,
and reapply every two hours — or more often if you're swimming or perspiring. Use a
generous amount of sunscreen on all exposed skin, including your lips, the tips of your ears,
and the backs of your hands and neck.
Wear protective clothing. Sunscreens don't provide complete protection from UV rays.
So cover your skin with dark, tightly woven clothing that covers your arms and legs, and a
broad-brimmed hat, which provides more protection than a baseball cap or visor does.
Some companies also sell photoprotective clothing. A dermatologist can recommend an
appropriate brand.
Don't forget sunglasses. Look for those that block both types of UV radiation — UVA and
UVB rays.
Avoid tanning beds. Lights used in tanning beds emit UV rays and can increase your risk
of skin cancer.
Be aware of sun-sensitizing medications. Some common prescription and over-thecounter drugs, including antibiotics, can make your skin more sensitive to sunlight.
Ask your doctor or pharmacist about the side effects of any medications you take. If they
increase your sensitivity to sunlight, take extra precautions to stay out of the sun in order to
protect your skin.
Check your skin regularly and report changes to your doctor. Examine your skin
often for new skin growths or changes in existing moles, freckles, bumps and birthmarks.
With the help of mirrors, check your face, neck, ears and scalp. Examine your chest and
trunk, and the tops and undersides of your arms and hands. Examine both the front and
back of your legs, and your feet, including the soles and the spaces between your toes. Also
check your genital area and between your buttocks.
References
1. What you need to know about skin cancer. National Cancer Institute.
http://www.cancer.gov/cancertopics/wyntk/skin. Accessed Oct. 31, 2013.
2. Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 5th ed. Edinburgh, U.K.; New York,
N.Y.: Mosby Elsevier; 2010. http://www.clinicalkey.com. Accessed Oct. 31, 2013.
3. Niederhuber JE, et al., eds. Abeloff's Clinical Oncology. 5th ed. Philadelphia, Pa.: Churchill Livingstone
Elsevier; 2014. http://www.clinicalkey.com. Accessed Oct. 31, 2013.
4. Kaposi sarcoma treatment (PDQ). National Cancer Institute.
http://www.cancer.gov/cancertopics/pdq/treatment/kaposis/HealthProfessional. Accessed Oct. 31, 2013.
5. Golden AK. Decision Support System. Mayo Clinic, Rochester, Minn. Sept. 3, 2013.
6. Gibson LE (expert opinion). Mayo Clinic, Rochester, Minn. Nov. 14, 2013.
Mar. 28, 2014
Original article: http://www.mayoclinic.org/diseases-conditions/skin-cancer/basics/definition/con-20031606
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