Description, Causes and Risk Factors:
A nevus exceeding 5 mm in diameter, with irregular, indistinct, or notched borders and mixed tan-to-black and pink-to-red color. Microscopically these are basally nested and scattered intraepidermal melanocyte with hyperchromatic nuclei larger than those of basal keratinocytes. If multiple and associated with a family history of melanoma, these nevi have a high risk of malignant change, but isolated dysplastic nevi in the absence of a family history of melanoma are less frequently pre-malignant.
Dysplastic nevi are unusual benign moles that may resemble melanoma. People who have them are at increased risk of developing single or multiple melanomas. The higher the number of these moles someone has, the higher the risk; those who have 10 or more have 12 times the risk of developing melanoma compared to the general population. Dysplastic nevi are found significantly more often in melanoma patients than in the general population.
Dysplastic nevi usually become clinically apparent at puberty or adolescence, but true dysplastic nevi have been described in prepubertal children. The dysplastic nevi continue to appear throughout life. Their number may vary greatly, from one to hundreds. In patients with multiple lesions, there is marked heterogeneity among lesions, resulting in a highly characteristic clinical phenotype. Counts of dysplastic nevi are highly correlated with total nevus counts (increasing as the total count increases), independent of a personal or family history of melanoma.
A chromosome instability disorder was observed in cell cultures from the normal skin and dysplastic nevi over three-generations in DNS (dysplastic nevi syndrome) families, leading to translocations, duplications and deletions; in another study on MM, translocations involving bands 11q24, 1q25 and Xq13 were observed in patients with DNS, in dysplastic nevi and in the normal skin as well; a loss of chromosome 9 was found in 2 out of 4 DN, suggesting that deletion/inactivation of a gene on 9p may be a primary event in melanocyte transformation; loss of heterozygosity (LOH) for markers flanking the CDKN2A on 9p was described in primary MM and in a metastasis; other putative tumor suppressor genes which could be involved in the process are located in 1p13, 10p, 10q, 11q and 6q15-q23.
Heredity appears to play a role in their development. Most commonly, dysplastic moles appear on sun-exposed skin, but can occur elsewhere and continue to develop after age 35. People who have dysplastic nevi and a family history of melanoma (two or more relatives with melanoma) are at increased risk of developing a melanoma during their Lifetime. Individuals who have dysplastic nevi and no family history of melanoma still may be at risk of developing a melanoma with the risk being 7 times higher than that of the general population.
Genetic factors also appear to be important; an autosomal dominant mode of inheritance has been reported in families with the dysplastic nevi - melanoma syndrome.
Medical reports indicate that about 2 to 8 percent of the Caucasian population have these moles. Heredity appears to play a part in their formation. Those who have dysplastic nevi plus a family history of melanoma (two or more close blood relatives with the disease) have an extremely high risk of developing melanoma. Individuals who have dysplastic nevi, but no family history of melanoma, still face a 7 to 27 times higher risk of developing melanoma compared to the general population — certainly a great enough risk to warrant monthly self-examination, regular professional skin exams and daily sun protection.
Dysplastic nevi are tan to dark brown and may have a mixture of colors, including tan, dark brown, and sometimes pink or black. The border is often irregular and indistinct and often fades into the surrounding skin. They may be raised or flat and can vary in size or shape.
The pathological diagnosis of dysplastic nevi requires the identification of both specific cytologic and architectural abnormalities. Interobserver agreement in the pathological diagnosis ofmelanocytic dysplasia is hampered by the lack ofuniversally accepted diagnostic criteria. In studiesthat use preset criteria for diagnosis, interobserveragreement is moderate-to-good.Reproducibility in grading atypia remains poor-to-moderate because of the nonuniform criteria used.
To diagnose sporadic dysplastic nevi syndrome with certainty, clinical examination of first-degree relatives is necessary.Although there has been concern that non-specialists might not reliably recognize the clinical phenotype, a recent study showed that identification of the phenotypewith the use of a specific scoring system was a skill that could be easily learned by Healthcare professionals who are not specialists.
Common moles do not need to be removed. Currently, no therapy is available to prevent the development of dysplastic nevi. Because melanomas may develop de novo on the skin and because the risk of any one dysplastic nevi changing into a melanoma is low, the prophylactic removal of all atypical moles is not recommended, because doing so would not necessarily prevent melanoma. Instead, accepted current treatment suggests removal of changing lesions and any lesion worrisome for melanoma.
Dysplastic nevi can be surgically removed after numbing with a local anesthetic; histological examination of the removed tissue to "rule out" cancer is often done. Some people choose to have them removed for Cosmetic reasons, if they are raised and located in areas where clothing irritates, such as the waistline, or if they are on the scalp and are irritated by hair brushing. Most moles can be cut off in simple In-office procedures. Dysplastic nevi do not need to be removed unless there are signs of changes observed. Moles and dysplastic nevi whose appearance suggests they may be cancerous should be removed and examined under a microscope. If they are found to be cancerous, additional skin in the surrounding area also must be taken to ensure all cancerous cells are removed. It is important for people with numerous dysplastic nevi or familial atypical nevi syndrome (that is, in a family whose members have lots of dysplastic moles) to have a full body screening from a dermatologist every three to twelve months beginning with the onset of puberty. Screening of relatives and full body photographs may also be recommended. Self exams, looking at one's own skin monthly, wearing sunscreen and sun protection is also an important part of a person's care.
If you have dysplastic nevi or if there is a history of melanoma in your family, you should have a dermatologist check all of your moles regularly. Your dermatologist will recommend how often you should have them checked.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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