A multicentre study of naevus‐associated melanoma vs. de novo melanoma, tumour thickness and body site differences*

Abstract

Background Whether melanoma in histological contiguity with a naevus [naevusassociated melanoma (NAM)] is distinctly different from melanoma arising de novo remains unclear. Objectives To determine whether the characteristics of de novo melanoma differ from NAM and are not due to naevus obliteration in thicker tumours. Methods We conducted a multicentre retrospective study of de novo melanoma and NAM in seven referral centres in Europe, Australia and the USA between 2006 and 2015. Results In a total of 9474 localized melanomas, de novo melanoma was associated with thicker tumours and body site differences compared with NAM. In the subset of T 1 melanomas (n = 5307), similar body site differences were found in multivariate analysis by body site. When compared with NAM, de novo melanoma was more likely to affect older individuals (≥ 70 years) when located on the head/neck [odds ratio (OR) 4Á65, 95% confidence interval (CI) 2Á55-8Á46], the trunk (OR 1Á82, 95% CI 1Á40-2Á36) or the upper extremity (OR 1Á69, 95% CI 1Á14-2Á50), was more likely to affect female patients when located on the lower extremities (OR 1Á36, 95% CI 1Á03-1Á80), and was more likely to be of the nodular melanoma subtype (OR 2Á23, 95% CI 1Á14-4Á35) when located on the trunk. De novo melanoma was less likely to have regression present compared with NAM.

Unsupervised Phenotype-Based Clustering of Clinicopathologic Features in Cutaneous Melanoma

“…Although the relationship between NAMs and DNMs has been carefully studied in the past ( Cymerman et al., 2016 ; Dessinioti et al., 2021 ; Lin et al., 2015 ; Martin-Gorgojo et al., 2018 ; Pampena et al., 2017 ; Reiter et al., 2021 ; Sheen et al., 2017 ), the unsupervised clustering suggests that NAMs are more similar to each other across all CP features than DNMs. In other words, NAMs (e.g., TC1–2) tend to be less mitogenic, less ulcerative, and less thick than DNMs (TC3–5).…”

“…(2015) reported significant associations in ulceration status, age, pathologic subtype, and truncal site in NAMs; however, their study exclusively selected patients undergoing sentinel lymph node biopsy. Furthermore, investigators have shown a central anatomic site (e.g., head, neck, and truncal areas) predisposition for DNMs and increased likelihood of nodular subtype DNMs that are truncally located ( Dessinioti et al., 2021 ). Pandeya et al.…”

“…While the relationship between NAM's and de novo melanomas (DNM's) has been carefully studied in the past (Lin et al, 2015;Reiter et al, 2021;Sheen et al, 2017;Cymerman et al, 2016;Martin-Gorgojo et al, 2018;Pampena et al, 2017;Dessinioti et al, 2021), the unsupervised clustering suggests that NAM's are more similar to each other across all clinicopathologic features compared to DNM's. In other words, NAM's (e.g.…”

“…Furthermore, investigators have shown a central anatomic site (e.g. head, neck, and truncal areas) predisposition for DNM's and increased likelihood of nodular subtype DNM's that are truncally located (Dessinioti et al, 2021). Pandeya and colleagues have also shown a significantly increased proportion of BRAF(V600E) mutations in NAM's (Pandeya et al, 2018).…”

Divergent pathways for melanoma: what is the role of genetics?

“…Despite the growing literature on the role of phenotypic characteristics in melanoma development, [6][7][8] the study of pathway-specific PRSs and melanoma risk is a recent development. PRSs are increasingly being applied to predict the risks of several complex disorders.…”