Predicting Melanoma in Small- and Medium-Sized Congenital Nevi

In patients with small- or medium-sized congenital nevi, peripheral location of the suspicious area and negative network may be the strongest dermatoscopic predictors of melanoma, researchers reported in a study published in the Journal of the American Academy of Dermatology.

The investigators screened the databases of 3 skin cancer referral centers to identify small- or medium-sized congenital nevi that were excised or biopsied to rule out melanoma developing in the nevus. Univariate and multivariate logistic regression were used to calculate crude and adjusted odds ratios, respectively.

A total of 119 tumors from 63 men and 55 women (mean age, 35.6 ± 16.3 years) were included in the analysis. From these cases, 87 (73.1%) were histopathologically diagnosed as congenital nevi and 32 (26.9%) as melanoma in congenital nevi.

After conducting a multivariate analysis, the researchers found the following strong melanoma predictors: peripheral location of the suspicious area (333.3-fold risk), negative network (106.5-fold risk), gray angulated lines (12.5-fold risk), and atypical network (6.6-fold risk).

“The importance of the peripheral location of the suspicious area is consistent with previous studies that described the macroscopic morphology of melanomas in congenital nevi and suggested that, also macroscopically, the suspicious area is usually eccentric,” the study authors commented. “Of the local dermatoscopic features evaluated in our study, negative network was the most potent melanoma predictor.”

Several study limitations include the retrospective design, and the inclusion of only biopsied lesions does not allow the generalization of the findings to all congenital nevi.

The investigators stated that the significance of gray angulated lines for diagnosing melanoma in small- and medium-sized congenital nevi is a novel finding.

“Gray angulated lines are known to typify melanoma on chronically sun-damaged skin, whereas melanoma development on pre-existing nevi is not considered to be driven by chronic sun exposure,” the study authors commented. “Further investigation is required to clarify if the angulated lines seen in melanomas on sun-damaged skin and in melanomas in congenital nevi correspond to similar histopathologic alterations. Theretofore, clinicians should consider that the feature may be seen in both of these melanoma types.”

Reference

Cuevas RG, Villani A, Apalla Z, et al. Dermatoscopic predictors of melanoma arising in small- and medium-sized congenital nevi [published online August 4, 2020]. J Am Acad Dermatol. doi: https://doi.org/10.1016/j.jaad.2020.07.116