Malignant Melanoma

Melanoma is a type of skin cancer that occurs in the cells that color the skin (melanocytes). It is more serious than the common basal cell or squamous cell skin cancers because it can spread to other parts of the body through the lymphatic system or the blood. It is the leading cause of all skin cancer-related deaths.

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What causes melanoma?

Although no one knows exactly what causes melanoma, one of the main risk factors appears to be exposure to ultraviolet (UV) radiation from too much sun or even from tanning booths. However, people who are exposed to intense sun over a short period of time (such as weekend tanners) are more at risk for melanoma than people such as farmers or sailors, who have a more consistent daily sun exposure.

While melanoma can occur in people who are darkly pigmented, people with fair skin who sunburn or freckle easily, especially those with red or blond hair, are at greater risk. Painful, blistering sunburns, especially in childhood or adolescence, can put people at risk. Melanoma also can run in families, especially those with a history of dysplastic nevus syndrome – a tendency to have many abnormally sized or shaped moles all over the body.

How is melanoma diagnosed?

Often, melanoma is discovered during a routine checkup or when a patient brings a suspicious mole to a doctor's attention. The first sign of melanoma is usually a change in the size, shape, or color of a mole. Another symptom is a change in how a mole feels; it can become tender, itchy, or hard. Melanoma can also appear on the body as a new mole. Look at the following chart to see what kinds of things to watch for and to show your doctor.

ABCDs of melanoma


Melanoma (malignant) lesions may be irregular in shape (asymmetrical). Benign (nonmalignant) moles are typically round (symmetrical).


Melanoma lesions may have irregular borders (ragged or notched edges). Benign moles usually have smooth, even borders.


Melanoma lesions may contain many shades of brown, blue, or black. Benign moles are usually a single shade of brown.


Melanoma lesions are often more than 6 millimeters in diameter (about the size of an eraser on a pencil). Benign moles are usually less than 6 millimeters in diameter.

Your doctor may want to perform a biopsy on a suspicious mole. A biopsy removes some or all of a mole or other growth for diagnosis by microscopic examination. For a suspicious mole, the doctor usually performs an excisional biopsy, which removes an elliptical wedge of skin that fully surrounds the mole and extends completely through the skin to enable the depth of the suspected melanoma to be accurately measured. The biopsy wound is closed with stitches and the sample is sent to the laboratory for analysis.

Stages of Melanoma

Stage IA
The tumor is 1.0 millimeter (mm) or less in thickness without ulceration. The tumor has not spread to the lymph nodes or distant organs.

Stage IB
The tumor is 1.0 mm or less in thickness with ulceration, or between 1.01 and 2.0 mm without ulceration. It has not spread to the lymph nodes or distant organs.

Stage IIA
The tumor is between 1.01 and 2.0 mm in thickness with ulceration, or between 2.01 and 4.0 mm without ulceration. It has not spread.

Stage IIB
The tumor is between 2.01 and 4.0 mm with ulceration, or greater than 4.0 mm without ulceration. It has not spread.

Stage IIC
The tumor is greater than 4.0 mm with ulceration. It has not spread.

Contact our dermatology office or your primary care physician if you have questions or concerns about melanoma.