Nevi of special site: Conservative treatment approach justified

August 5, 2009
Louise Gagnon

Louise Gagnon is a medical writer and editor based in Oakville, Ontario, Canada.

Nevi of special site can be seen not only in children and adolescents, but in adults up to age 35 as well, according to a recent study. A conservative approach to treating these nevi is justified given they do not appear to have the potential for malignancy.

San Francisco - Clinicians should avoid over-treating younger patients who present with nevi at special sites, according to an expert.

The nevi of special site appear in several areas, including the scalp of children and adolescents, as the scalp or the ears, and they occasionally may display features that create fears about melanoma, says Beth Ruben, M.D., associate professor of dermatology and pathology, University of California, San Francisco.

"These nevi sometimes cause concern among clinicians or parents because they are large or irregular, and among pathologists, as they may have architectural features or cytologic features that overlap with dysplastic nevus," Dr. Ruben tells Dermatology Times.

"Although they have features that overlap with dysplastic nevus, as is the case for nevi on other so-called special sites, they don’t appear to carry the same meaning, according to some studies," she says.


Research

Dr. Ruben and Betsy Perry, M.D., dermatology resident at the University of Utah, retrospectively reviewed 89 scalp and hairline nevi from 84 patients who ranged in age from 3 to 35, to find reproducible architectural and cytologic features in a blinded fashion.

Investigators surveyed architectural features, such as the distribution of junctional melanocytes including any irregular nesting patterns, adnexal involvement, suprabasal scatter, epidermal features such as squared rete ridges, and bridging of rete. They also characterized cytological features in lesional melanocytes, such as pigmented epithelioid, ordinary, large epidermal or dermal melanocytes, and dusty melanin within keratinocytes. Furthermore, they often encountered stromal features such as fibrosis and inflammatory infiltrate.

Specifically, 63 of 66 scalp nevi from patients 18 and younger had a predominance of large and/or irregularly placed junctional nests containing pigmented epithelioid melanocytes.

The same features were noted in 19/23 scalp nevi in patients aged between 19 through 35.

Of note, atypical features, such as suprabasal scatter of melanocytes or significant nuclear atypia, were not observed.

"We are not just seeing these in children and adolescents, as has been reported previously," Dr. Ruben says.

"We looked at a larger age range and found they occur in young adults as well," she says.


Conservative approach

Unnecessary procedures, such as re-excision of lesions that have been biopsied, are being performed when the nevi do not appear to have malignant potential, according to Dr. Ruben.

"We might be able to take a conservative approach and clinically monitor these lesions rather than have to excise them," says Dr. Ruben, based on the findings of this investigation and those in the literature.

Given that it can be technically difficult for clinicians to perform surgery on an area such as the scalp, it might be preferable to avoid invasive procedures to remove these nevi.

In some cases, particularly in young children, general anesthesia might be necessary to perform an excision, and general anesthesia carries its own set of risks, Dr. Ruben says.

"We have to look at these nevi in the context of the whole patient," she says. "One should also take into account if the patient has a worrisome family history or if they have multiple other irregular nevi."


Benign entities

A study published in the Journal of Cutaneous Pathology in 2007 concluded that atypical nevi of the scalp in adolescents are benign entities despite having similarities to melanoma.

The study noted that the relationship between the atypical nevi and melanoma remains nebulous, and the authors wrote that excision of the nevi using conservative margins "seems a recommendable procedure."

An article published in Modern Pathology in 2006 defined nevi of special sites as those appearing on the genital skin, acral skin, and flexural skin and, as the most important, "nevi of special sites."

The author wrote that it is important to "avoid overcalling such a lesion (nevi of special site) as a melanoma or a dysplastic nevus because this could lead to excessive treatment."

Still, clinicians need to engage in surveillance of nevi of special sites or dysplastic nevus. DT

Disclosure: Dr. Ruben reports no relevant financial interests.

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