Although nevi are among the strongest risk factors for melanoma, total nevus counts should not be the sole reason to perform skin examinations or to determine a patient’s at-risk status, according to a study published in JAMA Dermatology.1

Researchers sought to examine the link between age and the number of total nevi and atypical nevi as well as to establish if there was a relationship between total nevi or atypical nevi and tumor thickness.

A total of 566 patients with melanoma were surveyed within 3 months of diagnostic biopsy between May 2006 and March 2009. Total nevi and atypical nevi counts were performed at the first visit after diagnosis and were categorized as 0 to 20, 20 to 50, or more than 50 for total nevi; and 0, 1 to 5, or more than 5 for atypical nevi. Tumor thickness was categorized as 2.00 mm or less or 2.01 mm or greater. Analyses were stratified by patient age (younger or older than 60 years) and logistic regression was used to test for multiple variables.

Results showed that the number of total nevi categorized 0 to 20 was 66.4% (376 patients), 20 to 50 was 20.5% (116 patients), and more than 50 was 13.15% (74 patients). Atypical nevus counts were 0 (73.3%; 415 patients), 1 to 5 (14.5%; 82 patients), or more than 5 (12.2%; 69 patients). The presence of more than 50 total nevi in patients younger than 60 years was linked with a reduced risk of thick melanoma (odds ratio, 0.32; 95% CI, 0.12 – 0.81), and more than 5 atypical nevi compared with none was linked to thicker melanoma (odds ratio, 2.43; 95% CI, 1.02 – 5.75).

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The authors concluded that most patients with melanoma had few nevi and no atypical nevi and that younger patients should be educated on the increased risk of thicker melanomas associated with atypical nevi.

Reference

  1. Geller AC, Mayer JE, Sober AJ, et al. Total nevi, atypical nevi, and melanoma thickness: an analysis of 566 patients at 2 US centers [published online ahead of print March 2, 2016]. JAMA Dermatol. doi: 10.1001/jamadermatol.2016.0027.