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Melanocytic nevus

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Melanocytic nevus
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A mole, technically known as a melanocytic naevus, is a small, dark spot on human skin. According to the American Academy of Dermatology, the majority of moles appear during the first two decades of a person’s life while about one in every 100 babies are born with moles[citation needed]. Acquired moles are a form of benign neoplasm, while congenital moles are considered a minor malformation, or hamartoma. A mole can be either subdermal (composed of melanin), or a pigmented growth on the skin, formed mostly of a type of cell known as melanocytes. The high concentration of the body’s pigmenting agent, melanin, is responsible for their dark color. Moles are a member of the family of skin lesions known as naevi.

History

At one time in the 1950s and 60s, (and, to lesser extent, currently) a mole was known as a “beauty mark” when it appeared in certain spots on a woman’s face. Examples include Marilyn Monroe, model Cindy Crawford and singer Madonna. Madonna's facial mole -- below her right nostril -- has been surgically removed, possibly reflecting increasing public distaste for the former fetishizing of these blemishes. Almost everyone with light skin has at least one or two moles somewhere on their bodies while large numbers can be concentrated on the back, chest, and arms. Darker skin shades, however, tend to have fewer moles. Some folklore about moles includes the notion that picking at a mole can cause it to become cancerous or grow back larger. While chronic picking or irritation (by clothing) of a mole can be detrimental in many ways, it has not been associated with a higher incidence of cancer.[1] But while a mole may sometimes be removed by its bearer and may not grow back larger, the resulting scar can be larger. When a mole is bothersome, physicians usually recommend that it be examined by a dermatologist to see if it should be removed. The dermatologist or plastic surgeon can perform the procedure with an eye toward preventing a larger scar.

Cause

Sunlight

Some scientists suspect that overexposure to ultraviolet light, including excessive sunlight, may play a role in the formation of acquired moles.[2] However, more research is needed in this area.

Genes

Genes can also have an influence on a person’s moles.

Dysplastic nevi or atypical mole syndrome is a hereditary condition which causes the person to have a large quantity of moles (often 100 or more) with some larger than normal or atypical. This often leads to a higher risk of melanoma, a serious skin cancer.[3] A slight majority of melanomas do not form in an existing mole, but rather create a new growth on the skin. Nevertheless, those with more dysplastic nevi are at a higher risk of this type of melanoma occurrence.[4][5] Such persons need to be checked regularly for any changes in their moles and to note any new ones.

Appearance

According to the American Academy of Dermatology, the most common types of moles are skin tags, raised moles and flat moles.

Untroublesome moles are usually circular or oval and not very large.

If malignant

It often requires a dermatologist to fully evaluate moles. For instance, a small blue or bluish black spot, often called a blue nevus, is usually benign but often mistaken for melanoma.[6] Conversely, a junctional nevus, which develops at the junction of the dermis and epidermis, is potentially cancerous.[7]

A basic reference chart used for consumers to spot suspicious moles is found in the mnemonic, A-B-C-D. The letters stand for Asymmetry, Border, Color and Diameter. Sometimes, the letter E (for Evolving) is added. According to the American Academy of Dermatology, if a mole starts changing in size, color, shape or, especially, if the border of a mole develops ragged edges or becomes larger than a pencil eraser, it would be an appropriate time to consult with a physician. Other warning signs include a mole, even if smaller than a pencil eraser, that is different than the others and begins to crust over, bleed, itch, or becomes inflamed. The changes may indicate developing melanomas. The matter can become clinically complicated because mole removal depends on which types of cancer, if any, comes into suspicion.

Complications

Experts say that vast majority of moles are benign. Nonetheless, the National (U.S.) Cancer Institute reported 59,940 new cases of melanoma by June, 2007, with 8,110 deaths.[8]

Prevention

Sun exposure may drive up the total number of moles and cause them to become darker. Because studies have found that sunburns and too much time in the sun can increase the risk factors for melanoma, the American Academy of Dermatology recommends:

  • Staying out of the sun between 10 a.m. and 3 p.m. standard time (or whenever your shadow is shorter than your height).
  • Forgoing tanning booths
  • Wearing sun block, a hat and sunglasses outdoors

Mole removal

If a mole is highly suspicious of being a melanoma, then it might need to be removed and biopsied (microscopic evaluation by a pathologist). Other reasons for removal may be cosmetic, or because a raised mole interferes with daily living (e.g. shaving).

Moles can be removed by laser, surgery or electrocautery. They leave a red mark on the site which morphs back to the patient’s usual skin color in about two weeks. However, there might still be a risk of spread of the melanoma, so the methods of Melanoma diagnosis, including e.g. excitional biopsy.

Laser

In properly trained hands, some medical lasers are used to remove flat moles level with the surface of the skin, as well as some raised moles.

While laser treatment is commonly offered and may require several appointments, other dermatologists think lasers are not the best method for removing moles because the laser only cauterizes or, in certain cases, removes very superficial levels of skin. Moles tend to go deeper into the skin than non-invasive lasers can penetrate.

Healing

After a laser treatment a scab is formed, which falls off about seven days later, in contrast to surgery, where the fissure has to be stitched with sutures.

Surgery

Many dermatologic and plastic surgeons first use a freezing solution, usually liquid nitrogen, on a raised mole and then shave it away with a scalpel. If the surgeon opts for the shaving method, he or she usually also cauterizes the stump.

Because a circle is difficult to close with stitches, the incision is usually elliptical or eye-shaped.

Electrocautery

Electrocautery is also used for removing skin tags and only reaches the outermost level of skin so that scarring is not a problem.

References

  1. ^ P. Kaskel, P. Kind, S. Sander, R.U. Peter, G. Krahn (2000) Trauma and melanoma formation: a true association? British Journal of Dermatology 143 (4), 749-753
  2. ^ Arne van Schanke, Gemma M.C.A.L. van Venrooij, Marjan J. Jongsma, H. Alexander Banus, Leon H.F. Mullenders, Henk J. van Kranen and Frank R. de Gruijl. Induction of Nevi and Skin Tumors in Ink4a/ArfXpa Knockout Mice by Neonatial, Intermittent, or Chronic UVB Exposures. Cancer Res 2006; 66 (5), 2608-15.
  3. ^ Burkhart, C.G MPH, MD. Dysplastic nevus declassified; even the NIH recommends elimination of confusing terminology. SKINmed: Dermatology for the Clinician 2(1):12-13, 2003.
  4. ^ D.J. Pope, T. Sorahan, J.R. Marsden, P.M. Ball, R.P. Grimley and I.M. Peck. Benign pigmented nevi in children. Arch of Dermatology 2006;142:1599-1604
  5. ^ D.E. Goldgar, L.A. Cannon-Albright, L.J. Meyer, M.W. Pipekorn, J.J. Zone, M.H. Skolnick. Inheritance of Nevus Number and Size in Melanoma and Dysplastic Nevus Syndrome Kindreds. Journal of the National Cancer Institute 1991 83(23):1726-1733
  6. ^ Granter, Scott R. M.D.; McKee, Phillip H. M.D., F.R.C. Path.; Calonje, Eduardo, M.D.; Mihm, Martin C. Jr., M.D.; Busam, Klaus, M.D. Melanoma Associated with Blue Nevus and Melanoma Mimicking Cellular Blue Nevus: A Clinicopathologic Study of 10 Cases on the Spectrum of So-called ‘Malignant Blue Nevus’. American Journal of Pathology. 25(3):316-323, March 2001.
  7. ^ Hall J., Perry, VE Tinea nigrra palmaris: differentiation from malignant melanoma or juncional nevi. Cutis. 1998 Jul;62(1):45-6
  8. ^ http://www.nci.nih.gov/cancertopics/types/melanoma

See also

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