Melanoma is the third most common skin cancer in the United States, with about 50,000 new cases diagnosed each year. Melanoma arises from pigment cells, called melanocytes that give us our skin color and are located in the epidermis (outermost layer of the skin). Although melanoma usually occurs in sun-damaged skin, it may occur anywhere on the body.
Although melanoma most often remains confined to the skin for some time, it may eventually spread via lymph or blood vessels. In some cases, melanoma may spread (metastasize) to local lymph nodes, distant tissues or organs. When this happens, it can be fatal.
What Causes Melanoma?
Excessive exposure to sunlight is the most common cause of melanoma. Sunlight causes damage to melanocyte DNA and this is important because melanocyte DNA is the map or blueprint used to create the next generation of melanocytes. Each person has the ability to repair a certain amount of sun damage to melanocyte DNA, but repair ability varies widely from person to person and is probably inherited. People with excessive sun exposure who have minimal ability to repair sun damage are predisposed to form melanoma, whereas people with minimal sun exposure and maximun ability to repair sun damage are less likely to form melanoma.
Who Gets Melanoma? Anyone with a history of frequent sun exposure can develop melanoma. But people who have fair skin, light hair, or light eyes are at highest risk. Those whose occupations require long hours in the outdoors or who spend extensive leisure time in the sun are in particular jeopardy. Dark-skinned individuals are far less likely than fair-skinned to develop melanoma. Anyone with a personal or family history of melanoma is more likely to develop melanoma. How Serious is Melanoma? The prognosis of melanoma depends on variables that are unique in each case. The most important variable is thickness – thick melanomas are more dangerous than thin melanomas because they have greater access to vessels that may act as vehicles for spread (metastasis). Knowledge of melanoma thickness allows the surgeon to educate patients on their prognosis and guides the formulation of an optimal treatment plan in each unique case. What Does Melanoma Look Like? Melanoma is varied in appearance.Regular skin examination by a dermatologist allows for detection of early, and likely smaller and thinner melanomas. We recommend regular self-skin examination -- as often as once a month if you are at high risk. Be sure to include the scalp, backs of ears, neck, and other hard-to-see areas. (A full-length mirror and a hand-held mirror can be very useful). Your physician will suggest the correct time frame for follow-up visits, depending on your specific risk factors, such as skin type and history of sun exposure. Moles and Melanoma Some melanomas develop in preexisting moles. Most people have at least one mole on their body, and many people have more than 40. Most moles appear in the first 20 years of life and sun exposure may increase their overall number. New moles are usually flat and may be tan, pink, brown, or black in color. Although some moles do not change over time, many become raised and lighter in color. Most moles will slowly disappear, seeming to fade in time while others may form a “stalk,” making them resemble a skin tag. People who have many moles (greater than 100) and people who have many dysplastic or atypical moles are probably at increased risk to develop melanoma. Atypical moles are often large (larger than a pencil eraser in diameter) with irregular or asymmetrical shape, and uneven color. Recognizing the early warning signs of melanoma requires skin examination and an understanding of the ABCD’s of mole examination. Below is an introduction to the ABCD’s:
Asymmetry occurs when a mole’s shape cannot be divided into 2 mirror images.
Borders are irregular when they are ragged, jagged, or blend into the surrounding skin.
Color is irregular when there are more than 2 shades of brown, jet-black, red, white, or blue.
Diameter is too large if a mole is larger than 6mm in diameter (the diameter of a pencil eraser).
If moles display a change in these characteristics, a dermatologist should evaluate them. Imposters There are several benign skin lesions that may mimic melanoma. Some of these melanoma imposters are: A seborrheic keratosis is a benign, warty, occasionally pigmented growth commonly seen on the trunk and extremities. A lentigo is a flat, usually brown mark on the skin, and is often referred to as a “sun spot.” A venous lake is a collection of blood vessels under the skin, and often appears on the ears or lower lips.
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Mohs Surgery and Surgical Dermatology for Skin Cancer