Skin Cancer

Skin cancer is the uncontrolled growth of cancer cells in the skin. Left untreated, these cells can spread to other organs and tissues, such as lymph nodes and bone. Skin cancer is the most common cancer in the United States, affecting one in five Americans during their lifetimes, according to the Skin Cancer Foundation.

How Your Skin Works

Your skin works as a barrier to protect your body against things like water loss, bacteria, and other harmful contaminants. The outermost layer, the epidermis, is the layer in constant contact with the environment. While it sheds skin cells regularly, it can sustain damage from the sun, infection, or cuts and scrapes. The epidermis is made up of several different types of cells.

Actinic Keratosis

Actinic keratosis is another type of red, pink, or rough patch of skin on sun-exposed areas of the body. This is the most common form of precancer and can develop into basal cell carcinoma in patients with a history of two or more skin cancers (Skin Cancer Foundation, 2012). While rare, these lesions can also be a precursor for squamous cell carcinoma, and the two are often misdiagnosed as one another.

Basal Cell Carcinoma

Basal cells make up the lowest layer of the epidermis, the basal layer. Cancer inside this area is known as basal cell carcinoma, and it comprises about 80 percent of all cases of skin cancer (Columbia University, 2009). Most common in the head and neck, basal cell carcinoma is a slow-growing cancer that rarely spreads to other parts of the body. It usually shows on skin as raised, waxy pink bumps. Infiltrative basal cell carcinoma can appear translucent with blood vessels near the skin’s surface.

Squamous Cell Carcinoma

Squamous cell carcinoma affects cells in the middle layer of the epidermis. It is typically more aggressive than basal cell carcinoma.  It appears as red, scaly, and rough skin lesions, typically on sun-exposed areas such as the hands, head, neck, lips, and ears. Similar red patches may be squamous cell carcinoma in situ (Bowen’s disease), the earliest form of squamous cell cancer.


Less common than other types, melanoma is by far the most dangerous, causing about 75 percent of all skin cancer-related deaths (American Melanoma Foundation, 2009). It occurs in the skin cells that create pigment, and it creates moles or lesions that follow an ABCDE pattern in their irregularities:

  • asymmetrical shape
  • border irregularities
  • color
  • diameter
  • evolution of the lesion

The Four Major Types of Melanoma

  • Superficial spreading melanoma: The most common type; lesions are usually flat, irregular in shape, and contain varying shades of black and brown. It can occur at any age.
  • Lentigo maligna melanoma: Usually affects the elderly; involves large, flat, brownish lesions
  • Nodular melanoma: Can be dark blue, black, orreddish-blue, but may have no color at all. It usually starts as a raised patch.
  • Acral lentiginous melanoma: The least common type; typically affects the palms, soles of the feet, or under finger and toenails (AAD, 2010).

Kaposi’s Sarcoma

While not typically considered a skin cancer, Kaposi’s sarcoma is another type of cancer that involves skin lesions that are brownish-red to blue in color and usually found on the legs and feet. It affects the cells that line blood vessels close to the skin. This cancer is caused by a type of herpes virus and is typically associated with patients with AIDS.

Who is at Risk?

While there are several different types of skin cancers, most share the same risk factors, including:

  • prolonged exposure to UV rays found in sunlight
  • being over the age of 40
  • family history of skin cancers
  • fair complexion
  • organ transplant

However, young people or those with dark complexion can still develop skin cancer.

Get More Information

The quicker skin cancer is detected, the better the long-term outlook. Check your skin regularly. If you notice abnormalities, consult a dermatologist for a complete examination. Learn how to self-examine your skin.

Preventive measures, such as wearing sunscreen or limiting your time in the sun, is your best protection against all types of skin cancer.

Learn more about skin cancer and sun safety.

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