Distribution Analyses of Acquired Melanocytic Naevi on the Trunk

Abstract

Acquired melanocytic naevi (AMN) are a well-known risk factor for the development of melanoma. Whereas previous studies have reviewed AMN distributions on individual body sites, the clinical distribution of AMN on the adult trunk has not been thoroughly investigated. We studied 40 participants with 1,282 naevi >5 mm, of which 781 were located on the trunk. Remarkably, 70% of these truncal naevi were located on the back and we produced a continuous mathematical description of decreasing naevus frequency moving dorsolaterally from the back midline. Furthermore we found that for both sexes the mean naevus size was larger on the front as well as on the lower trunk. This distinct pattern, whilst probably being unwritten knowledge (in the dermatology domain), has not been discussed before.

Classification of naevus distribution patterns in the Brisbane naevus morphology study

“…The back was the most common site of naevi for both sexes, which is consistent with previous studies [54,62,91]. Men were found to have a higher naevus count on the back and chest/abdomen region in comparison to women [59]. This distribution pattern has been previously described and has typically also been associated with a corresponding increase in naevus count in the lower limbs in women [54,91].…”

“…In population studies carried out in adults, the anatomical distribution of naevi described to date has been predominantly focused on the back, arms and legs. This is largely due to these sites receiving the greatest level of intermittent sun exposure over the course of time and have also been shown to be common sites for melanoma [59][60][61][62].…”

“…Parallel studies assessed the number of naevi or naevus density, but focus on each anatomical site independently [59,77].…”

Melanocortin 1 receptor (MC1R) polymorphisms’ influence on size and dermoscopic features of nevi

“…As previously reported, higher TBNC was observed in males (OR: 1.45, 95% CI [1.25-1.68], adj. p-value <.001), in light-skinned individuals (OR: 2.76, 95% CI [1.48-5.18], p-value = .001) (Aalborg, Morelli, Byers, Mokrohisky, & Crane, 2010;Aguilera et al, 2009;Blake et al, 2014;Echeverría, Bulliard, Guillén, & Nagore, 2014) and correlates with height (OR: 1.06, 95% CI [1.02-1.10], p-value = .003) (Ribero et al, 2016).…”