Among younger patients, thick melanomas may be commonly found in those with fewer total nevi but more atypical nevi, suggesting that clinicians not rely on total nevus count as the sole reason to perform skin examinations to determine risk, according to a study published in JAMA Dermatology.1
Researchers led by Alan Geller, MPH, RN, of the Harvard T. H. Chan School of Public Health in Boston, Massachusetts, conducted a survey of 566 patients with melanoma within 3 months of diagnosis at 2 academic sites as well as an affiliated Veteran Affairs medical center.
Total and atypical nevi count was performed on first visit after diagnosis; patients were categorized as 0 to 20, 20 to 50, or more than 50 total nevi, and 0, 1 to 5, or more than 5 atypical nevi. Tumor thickness was categorized as 2.00 mm or less or as 2.01 mm or greater, with all analyses stratified by age of younger than 60 years or 60 years or older.
Logistic regression was used to test associations while controlling for factors such as age, sex, anatomic location of melanoma, and histologic subtype.
Among all patients, total nevi was classified as 0 to 20 in 66.4%, 20 to 50 in 20.5%, or more than 50 in 13.1%. Atypical nevus count was 0 in 73.3%, 1 to 5 in 14.5%, or more than 5 in 12.2%.
In addition, the researchers found, in patients younger than 60 years, the presence of more than 50 total nevi was associated with a sharply reduced risk of thick melanoma, while the presence of 5 atypical nevi compared with no atypical nevi was associated with thicker melanoma.
“Younger patients should be educated on the increased risk of thicker melanoma that is associated with having more atypical nevi,” the authors concluded.
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.