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Melanoma

What Is Melanoma?

Melanomas are cancerous (malignant) tumors involving specialized cells called melanocytes. Melanocytes have the unique ability to produce the pigment melanin and can be found in the skin, mucous membranes, eye, adrenal gland, and brain. Melanomas have a peculiar tendency to spread to distant sites (metastasize) at an early stage of growth and to grow in an uncontrolled fashion at the new site. This results in organ damage and ultimately death. When melanoma spreads from its original site, it is referred to as metastatic melanoma. The incidence of this type of cancer has recently been rising, and it is the single most common cause of death from any skin disease.

What Causes Melanoma?

Like most cancers, the cause of melanomas involves interplay between genetic and environmental factors. It is generally agreed that ultraviolet-light-induced mutations in melanocytes is the single most important environmental factor in the induction of cutaneous melanomas. The fact that melanomas are difficult to produce experimentally, as well as their appearance in areas of the body in which no light exposure occurs, has fueled some controversy as to causation. Melanomas tend to occur on sun-exposed skin in lightly pigmented individuals. On the other hand, there is a correlation between exposure to sunlight as defined by the earth's latitude and the incidence of melanoma. For example, melanoma is much more common in sunny areas, such as Arizona, than in Seattle. About twenty percent of melanomas are produced by heritable genetic mutations. Some of these genes have been identified. The remainder seem to be due to ultraviolet light-induced changes in genes (mutational events).

What Are Symptoms and Signs of Melanoma?

Melanomas most often arise on normal skin, but they may also occasionally occur in conjunction with a benign nevus (beauty mark or birthmark). The identification of potentially malignant pigmented lesions is best remembered by using the first five letters of the alphabet as follows:

  • A for asymmetry
  • B for border irregularity
  • C for color multiplicity
  • D for diameter greater than ¼ inch
  • E for evolution (change) in the size and/or shape

Melanomas may ulcerate and bleed and occasionally cause these lesions to itch or burn. In summary, melanomas are most often pigmented, asymmetric with respect to color and shape, and tend to enlarge or change over time. The presence or absence of hair follicles is of no significance.

Medically Reviewed by a Doctor on 10/2/2015

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Patient Comments & Reviews

The eMedicineHealth doctors ask about Melanoma:

Melanoma - Patient Experience

Were you diagnosed with Melanoma? Please describe your experience.

Melanoma - Treatment

How was your melanoma treated?

Metastatic melanoma may have no symptoms at first.

Metastatic Melanoma Symptoms and Signs

When melanoma spreads through the bloodstream, the signs and symptoms will depend upon which organ system is involved and how much the tumor has grown there. Metastatic melanoma may be initially painless and symptom-free or may demonstrate ongoing problems according to the site. With lymphatic spread, swollen lymph glands or a string of nodules in the skin may be the presentation. These also are usually painless.



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