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“Moles” and Melanoma

1.   What are moles and melanoma?

Moles (known medically as “nevi”) are flat or raised benign growths appearing anywhere on the skin, usually brown, although sometimes pinkish, skin-colored or even bluish in color. Nevi are composed of skin cells that specialize in producing pigment (melanocytes) localized in either in the outer skin layer (epidermis) or within the underlying skin layer (dermis).  The natural history of a nevus is to fade in color and to become more raised over a person’s lifetime.  Malignant skin cancer (melanoma) may arise in a pre-existing nevus or may appear as a “new” nevus.  The number of melanoma cases worldwide is increasing faster than any other cancer. The annual increase in incidence rate varies between populations, but in general has been in the order of 3-7% per year for fair-skinned Caucasian populations. The estimates suggested a doubling of melanoma incidence every 10-20 years.   In Australia, melanoma of the skin is the fourth most common cancer among males (after prostate cancer, bowel cancer and lung cancer) and the third most common cancer among females (after breast cancer and bowel cancer). Since certain types of nevi have a higher risk of becoming cancerous, individuals of all skin type should visit a dermatologist at least once a year for a thorough skin examination.  If a new nevus or a change in a pre-existing nevus is noticed, a dermatologist should be seen right away for evaluation and possible biopsy for microscopic diagnosis.  In addition, all individuals should know the ABCD’s of skin cancer, listed below.

2.   What do nevi and melanoma look like?

Nevi generally begin as tan, pink, brown, black or bluish, flat, round, skin growths that resemble freckles.  They tend to arise in a random pattern on the body. In time, moles slowly grow larger, and often grow hairs or become raised and fleshy and can appear tag-like. Certain nevi may appear surrounded by a halo of lighter colored skin. 

Research has shown that certain types of nevi have a greater risk for developing into malignant melanoma, a dangerous cancer that can be deadly.  An individual exposed to one or multiple severe, blistering sunburns may have a greater risk for melanoma.  Individuals with greater than 100 moles may also have a higher chance of developing melanoma.  In addition, moles present at birth or shortly after birth that are larger than 8 inches in diameter also carry an increased risk of developing melanoma in a person’s lifetime.  The following ABCD’s for assessment of nevi and melanoma may help distinguish whether a nevus should be evaluated by a dermatologist.

The ABCDE’s of Melanoma

All individuals should understand and recognize the early signs of melanoma.  A nevus should be checked promptly by a dermatologist if any of these characteristics are observed:   A:  Asymmetry, when there is asymmetry, or a difference in the shape of one side of the nevus compared to the other.  B:  Border, or Bleeding, when the borders or edges of the nevus are blurred, inconsistent, ragged, or irregular.  Also, when bleeding of the nevus is observed.  Nevi that bleed due to nicking during regular hair-shaving are not associated with any increase in melanoma; however, removal may be desired to reduce discomfort or irritation in concerned individuals.  C:  Color, Changes, or Concern, when there are color spots, or a difference in coloration throughout the nevi such as different shades of tan, brown, black, blue, red, or white.  A mole with any changes such as itching, pain, bleeding, or discomfort should be checked by a dermatologist.  In addition, if an individual is frequently concerned or feels uncomfortable about the presence of a nevus, then it should be checked.  D:  Diameter, when the diameter of the nevus is larger than 6mm (approximately the diameter of a pencil eraser). E: Evolving.  This latest addition to the ABCD’s recognizes evolving lesions (i.e. lesions that change over time).  The parameter E has been included to emphasize the importance of evolving pigmented lesions in the natural process of melanoma progression. Evolving lesions are defined as those which change in respect to size, shape and symptoms, surface or shades of color. Changes in size, elevation and color taken together is the most probable pointer to melanoma malignancy, other symptoms being bleeding, itching, tenderness and ulceration. Lesions that are enlarged and non-uniform are four times more likely to be melanomas than those which did not meet these criteria.

Lesions that may look like melanoma

Other harmless, pigmented growths that are not nevi may appear on the skin.  Freckles are very common, pea-size or smaller, brown or tan spots that darken with sun exposure and may completely fade during the winter.  Unlike nevi, freckles are generally limited to the sun-exposed skin.  Seborrheic Keratoses are brown, dome-shaped, wart-like growths on the face or trunk that appear waxy or “stuck-on” to the skin.  These are harmless, but may be removed if they regularly become irritated from chafing against clothes or jewelry.  Solar lentigines, or “sun spots,” are gray-brown flat growths caused by sun exposure that generally do not fade during winter.

3.   Who gets nevi and melanoma?

Most nevi appear during the first 20-30 years of life.  Nevi are seen equally among males and females, and new nevi are seen more commonly among fairer-skinned individuals.  In addition, melanoma is more prevalent among fair-skinned individuals, however, melanoma is known to occur in all skin types, even African-American skin.  Melanoma may arise in as many as 1 – 5% of very large congenital nevi (present at birth).   In addition, individuals with family histories of skin cancer of any kind have a greater risk of developing melanoma.

4.   What causes nevi and melanoma?

Nevi consist of small clusters of melanocytes, which continue to proliferate and spread into the lower layers of the skin (dermis), and sometimes even deeper, along hair follicles.  Over many years, these cells differentiate and become mature, unchanging cells.  It is when these cells become “atypical,” and begin proliferating without differentiating or maturing, that malignant melanoma can occur.

5.   What Triggers nevi and melanoma?

Nevi may appear, darken, or enlarge with exposure to sunlight, birth control pills and some other medications, or other hormonal changes, such as during pregnancy.  A higher risk for melanoma is also seen among individuals with numerous nevi (100 or greater).   

6.   How can nevi and melanoma be treated?

If a nevus is “suspicious” to a dermatologist, or if an individual desires its removal, it may be excised for evaluation under a microscope.  A shave excision or a deeper excision may be performed depending on the appearance of the nevus.  Both of these procedures are painless procedures after a simple numbing shot is given.  If a melanoma or “atypical” nevus is diagnosed after microscopic examination (“biopsy”), the dermatologist may perform a deeper and wider re-excision to make certain that all the involved tissue is fully removed.  This may leave a fine-line scar at the site of the excision, however the procedure itself is painless after numbing is administered.  For more information on nevus removals or to schedule an annual skin examination, please call and speak with a representative at the Berman Skin Institute.

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