Made in the Shade: Get Screened for Skin Cancer

BIDMC Contributor

SEPTEMBER 01, 2010

skin cancer

Two Main Types of Skin Cancers

There are 2 main types of skin cancers : keratinocyte cancers (basal and squamous cell skin cancers) and melanomas. 

Basal and squamous cell skin cancers are the most common cancers of the skin. They develop from cells called keratinocytes, the most common cells in the skin. 

Melanomas are cancers that develop from melanocytes, the cells that make the brown pigment that gives skin its color. Melanocytes can also form benign (non-cancerous) growths called moles. 

There are several other types of skin cancers as well, but these are much less common. 

It is important for doctors to tell these types of skin cancer apart, because they are treated differently. It is also important for you to know what melanomas and basal and squamous cell skin cancers look like. That way, you can find them at the earliest possible stage, when they are cured most easily.

Basal and Squamous Cell cancers (Keratinocyte Cancers)

Basal cell cancers and squamous cell cancers are the most common cancers of the skin. They develop from skin cells called keratinocytes. Both basal cell and squamous cell cancers are found mainly on parts of the body exposed to the sun, such as the head and neck, and their occurrence is related to the amount of sun exposure a person has had.

These cancers (especially basal cell cancers) rarely spread elsewhere in the body and are much less likely than melanomas to be fatal. Still, it is important to recognize them. If left untreated, they can grow quite large and invade into nearby tissues, causing scarring, disfigurement, or even loss of function in some parts of the body.


Melanomas can occur anywhere on the body, but are more likely to develop in certain locations. The trunk (chest and back) is the most common site in men. In women, the legs are the most common site. The neck and face are other common sites. 

Melanoma occurs much less often than basal cell and squamous cell skin cancers, but it can be far more serious. Like basal cell and squamous cell cancers, melanoma is almost always curable in its early stages. But if left alone, melanoma is much more likely than basal or squamous cell cancer to spread to other parts of the body, where it can be very hard to treat.

Get Your Skin Checked by Your Doctor

As part of a routine cancer-related checkup, your doctor should check your skin carefully. They should be willing to discuss any concerns you might have about this exam.

How to Check Your Own Skin

It's important to check your own skin, preferably once a month. A self-exam is best done in a well-lit room in front of a full-length mirror. You can use a hand-held mirror to look at areas that are hard to see. A spouse or close friend or family member may be able to help you with these exams, especially for those hard-to-see areas like your back or the back of your neck. 

The first time you inspect your skin, spend time carefully going over the entire surface of your skin. Learn the pattern of moles, blemishes, freckles, and other marks on your skin so that you'll notice any changes next time. Any trouble spots should be seen by a doctor.

What should I look for?

1. Basal and Squamous Cell Cancers

Basal cell cancers and squamous cell cancers are most often found in areas that get exposed to a lot of sun, such as the head, neck, and arms, but they can occur elsewhere. Look for new growths, spots, bumps, patches or sores that don't heal after 2 to 3 months. Both of these types of skin cancer may develop as a flat area showing only slight changes from normal skin.

Basal cell carcinoma

  • Basal cell carcinomas  often look like flat, firm, pale areas or small, raised, pink or red, translucent, shiny, waxy areas that may bleed after a minor injury. They may have one or more abnormal blood vessels, a lower area in their center, and/or blue, brown, or black areas. Large basal cell carcinomas may have oozing or crusted areas.

Squamous cell carcinoma

  • Squamous cell carcinomas may look like growing lumps, often with a rough, scaly, or crusted surface. They may also look like flat reddish patches in the skin that grow slowly. 
  • Actinic keratosis , also known as solar keratosis, is a skin condition that is sometimes pre-cancerous and is caused by too much sun exposure. Actinic keratoses are usually small (less than ¼ inch), rough spots that may be pink-red or flesh-colored. Usually they develop on the face, ears, back of the hands, and arms of middle-aged or older people with fair skin, although they can occur in younger people or on other sun-exposed areas of the skin. People with one actinic keratosis usually develop many more. Some can grow into squamous cell cancers, but others may stay the same or even go away on their own. Because they can turn cancerous, such areas should be looked at by a doctor. Your doctor can then decide whether they should be treated.
2. Melanomas


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. Another important sign is a spot that looks different from all of the other spots on your skin (known as the ugly duckling sign ). If you have any of these warning signs, have your skin checked by a doctor. 

The ABCD rule is another guide to the usual signs of melanoma. Be on the lookout and tell your doctor about any spots that match the following description:

  • 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 sometimes with patches of pink, red, white, or blue. 
  • D is for Diameter: The spot is larger than 6 millimeters across (about ¼ inch -- the size of a pencil eraser), although melanomas can sometimes be smaller than this.

Some melanomas do not fit the rules described above, so it is important to tell your doctor about any changes in skin lesions, new skin lesions, or growths that look different from the rest of your moles. 

Other warning signs are:

  • A sore that does not heal 
  • Spread of pigment from the border of a spot to surrounding skin 
  • Redness or a new swelling beyond the border 
  • Change in sensation -- itchiness, tenderness, or pain 
  • Change in the surface of a mole -- scaliness, oozing, bleeding, or the appearance of a bump or nodule

What if I find something suspicious?


It's important to know the difference between a harmless mole and a spot that might be a melanoma. 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 ¼ inch across, or about the width of a pencil eraser. Moles can be present at birth or they can appear later. Several moles can appear at the same time.

Once a mole has developed, it will usually stay the same size, shape, and color for many years. Moles may fade away in older people. 

Most people have moles, and almost all moles are harmless. But it is important to recognize changes in a mole -- such as its size, shape, or color -- that suggest a melanoma may be developing. 

Irregular border on mole

Be sure to show your doctor any area that concerns you. A qualified doctor should be able to identify any suspicious areas you may have.

Above content provided by the American Cancer Society in partnership with Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor. 

Posted September 2010



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Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.