Study: Atypical Moles Not Precursors to Melanoma

Observation and frequent skin surveillance may be an effective way of monitoring moderately dysplastic nevi with positive histologic margins, a multicenter, retrospective cohort study found.

No cutaneous melanoma (CM) developed at the biopsied site among 438 patients over 6.9 years of follow-up with that strategy of complete clinical removal of the pigmented area but leaving positive histologic margins, then monitoring with standard visualization and dermoscopic examination.

While one case in particular was identified as melanoma in situ, that patient did not have a clinical recurrence at the biopsy site after 5 years of clinical follow-up, reported Caroline Kim, MD, of Beth Israel Deaconess Medical Center in Boston, and colleagues.

"These data underscore the fact that dysplastic nevi are not obligate precursors of CM," they wrote in JAMA Dermatology.

Rather, these appeared to be a marker of a high-risk patient: 22.8% developed melanoma outside the biopsy site.

In the multivariate analysis, a history of CM was significantly correlated with risk of development of subsequent CM at a separate site (OR 11.74, P<0.001). Likewise, there was also a significant association between a history of CM and prior biopsied dysplastic nevi (OR 2.55, P=0.01).

Without clear proof that such nevi are not precursor lesions to melanoma, clinical practice has been all over the map on how to manage them, noted Adewole Adamson, MD, MPP, of Dell Medical School in Austin, and Kelly Nelson, MD, of the University of Texas in Houston, in an accompanying editorial.

While the study wasn't the kind of randomized clinical trial that could incontrovertibly prove lack of melanoma transformation, such a trial would take tens of thousands of patients followed for many years, they noted.

Meanwhile, they called the researcher's strategy a reasonable one: "The evidence continues to mount that observation of moderately dysplastic nevi is a reasonable option, even for dysplastic nevi with focal positive histologic margins after complete clinical removal. The gap in the evidence for this recommendation continues to close."

Relying on close observation of moderately dysplastic nevi with positive histologic margins "may save patients the morbidity of reexcision, while our recommendation for surveillance for patients with 2 or more biopsied dysplastic nevi (of which 1 is moderately dysplastic) may facilitate early detection or prevention of future CM," the investigators wrote.

"Both recommendations have the potential to significantly reduce the healthcare cost and resource burden associated with reexcisions and CM diagnosis," they noted.

The study evaluated 193 women and 245 men (average age of 46.7) with a total of 467 moderately-dysplastic nevi with positive histologic margins.

There was a clinical recurrent pigmentation rate of 1.2% at the biopsy site, and 7.5% of cases were upgraded in degree of atypia during follow-up.

Central dermatopathologic review of 40 cases, as a result of two sites being pooled owing to low numbers, yielded agreement in 87.5% of cases.