Low mole count may predict melanoma risk

February 6, 2016

Melanoma patients with fewer than 50 nevi may develop more aggressive melanomas than those with greater than 50 nevi, underscoring the need for education and consideration for skin cancer screening in all patients based on their overall risk.

Atypically pigmented lesion on lateral right foot of a patient with few nevi with 10x dermoscopic magnification revealing atypical patterns including blue-white veil, milky-red area, and irregular globules. Histopathology revealed a 3.3 mm/Clark IV melanoma. 

Caroline C. Kim, M.D.A recent study of melanoma patients found that individuals with fewer than 50 nevi tended to develop more aggressive melanoma compared to those patients with more than 50 nevi.

The eye-opening results not only highlight the necessity of regularly performed skin cancer screenings but also the need for appropriate skin cancer education in patients with nevi, regardless of the nevus count.

High nevus count (HNC), defined as more than 50 nevi, is a well-known and clinically useful risk factor for melanoma, as patients can be readily identified and referred for screening. However, melanomas can also occur in patients with low nevus count (LNC), defined as less than 50 nevi, and these patients at risk may not be as easily identified.

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Although individuals with more than 50 nevi can have an increased risk of developing melanoma, those with fewer nevi must still be vigilant, as having fewer nevi does not negate their risk for developing this deadly disease.

Consider all patients for screening

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“All patients, regardless if they have more or fewer nevi, really need to know more about melanoma and get educated in this regard, and need to be considered for screening,” says Caroline C. Kim, M.D., Director, Pigmented Lesion Clinic, Associate Director, Cutaneous Oncology Program, department of dermatology, Beth Israel Deaconess Medical Center, Harvard Medical School in Boston, Mass., and co-author of the study.

NEXT: Finding the  pattern

 

Atypically pigmented lesion on lateral right foot of a patient with few nevi with 10x dermoscopic magnification revealing atypical patterns including blue-white veil, milky-red area, and irregular globules. Histopathology revealed a 3.3 mm/Clark IV melanoma. 

 

Atypically pigmented lesion on lateral right foot of a patient with few nevi.Finding the pattern

Dr. Kim and fellow investigators conducted a retrospective chart review study evaluating all melanoma patients who were recently seen in the course of one year in their Pigmented Lesion Clinic/Cutaneous Oncology Program. The clinicopathologic features of melanomas that arise in HNC vs LNC patients were investigated, as well as the influence of having atypical or dysplastic nevi, another risk factor of melanoma. The study included 281 melanoma patients, with 89 having more than 50 nevi and 192 having fewer than 50 nevi.

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Results showed that there were numerous differences between HNC and LNC patients including age at melanoma diagnosis (41 vs 51 years), Breslow depth (1.3 mm vs 1.7 mm), mitotic rate (2 vs 4 mits/mm2), and stage of melanoma (Stage I: 65% vs 39%, Stage II: 10% vs 17%, Stage III: 21% vs 33%, Stage IV: 4% vs 8%).

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Patients with HNC and atypical or dysplastic nevi vs those with LNC and no atypical or dysplastic nevi were also more likely to have a family history of melanoma, and to have a melanoma with dark pigmentation, without ulceration, and with truncal location.

NEXT: Divergent pathways?

 

Atypically pigmented lesion on lateral right foot of a patient with few nevi with 10x dermoscopic magnification revealing atypical patterns including blue-white veil, milky-red area, and irregular globules. Histopathology revealed a 3.3 mm/Clark IV melanoma. 

Divergent pathways?

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These results may reflect that patients with more nevi are currently better identified, educated and screened for an earlier diagnosis, however, it also supports potentially different biological pathways for melanoma in patients with more and fewer nevi. A divergent pathway suggests that there may be different genetics and melanoma mutations in these two populations that could render melanomas more aggressive in patients with fewer nevi, and less aggressive in patients with more nevi.

Educate all patients

According to Dr. Kim, clinicians must strive to educate all patients about their melanoma risk as well as to inform them of the warning signs for melanoma. She says that clinicians should encourage their patients to consider sun protection and to schedule skin cancer screenings.

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“I’ve heard from multiple patients after their diagnosis that they never knew that they needed to be screened for skin cancer, or that they were at risk for melanoma, because they didn’t have moles. We need to make sure that we educate all patients about melanoma warning signs, and a patient should really be considered for melanoma screening if they have any melanoma risk factor including fair skin, a history of extensive UV exposure, a family history of melanoma, a history of immunosuppression, or a prior malignancy, in addition to having more than 50 nevi or atypical or dysplastic nevi,” Dr. Kim says.

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In contrast to screening for other cancers such as breast cancer and colon cancer, Dr. Kim says that, at present, there are no clear guidelines in place for skin cancer screening for the population. As such, it is up to the physician and the individual patient to initiate dermatology screening for skin cancer including melanoma, which emphasizes the importance of skin cancer education in the general population.

NEXT: Tools of the trade

 

Atypically pigmented lesion on lateral right foot of a patient with few nevi with 10x dermoscopic magnification revealing atypical patterns including blue-white veil, milky-red area, and irregular globules. Histopathology revealed a 3.3 mm/Clark IV melanoma. 

Tools of the trade

In addition to dermoscopy, Dr. Kim utilizes total body digital photography to better identify, document and map out the nevi in her patients. She will ask her patients to return for further screening check-ups every year or even sooner, depending on other personal risk factors present in the individual patient. The use of the ABCDE rule (Asymmetry, Border, Color, Diameter, Evolving) in skin cancer screening is an invaluable tool in quickly identifying suspicious lesions. However, Dr. Kim says that patients need to understand that melanoma does not always develop from a present mole but can also arise de novo. This fact emphasizes that a patient with any number of moles is at risk for melanoma.

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Patients should also be aware of the “ugly duckling” rule, Dr. Kim says, which refers to a lesion, of any color, pink to black, that looks different from any other lesion present on their skin. An ugly duckling lesion can be a sign of a melanoma, especially if it is changing rapidly, and should be evaluated by a dermatologist without delay.

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“It is crucial that we educate all of our patients in regards to the risk of melanoma no matter how many moles they have, as those with fewer moles may fall off the radar. All patients need to be educated in depth about the warning signs of melanoma, not just the moles changing in size, shape and color, but also about new atypical lesions keeping the ugly duckling rule in mind,” Dr. Kim says.

Dr. Kim reports no relevant disclosures.