Risk factors of lentigo maligna as compared to other melanoma subtypes

Lentigo maligna (LM) exhibits a particular epidemiological profile compared to other histopathologic subtypes of melanoma, with a propensity for the head and neck area and a higher mean age at diagnosis. Few small-scale studies have exclusively evaluated the risk factors for the development of LM.

This study aims to compare LM to other histological subtypes of melanoma for the prevalence of known melanoma risk factors, including pigmentary characteristics, history of occupational sun exposure, nevus count, and familial melanoma history.

We conducted a case-control study of 152 patients with LM and 784 patients with other melanoma subtypes (OM). The Mann-Whitney t-test and Pearson chi-squared test were used to detect differences between the two groups in continuous and categorical variables, respectively. Univariate and multivariate logistic regression models were then constructed to identify risk factors for developing LM compared to other melanoma subtypes.

In multivariate logistic regression analysis, LM was positively associated with a lentigines count >50 and occupational sun exposure compared to OM (OR 2.10, 95% CI 1.35-3.29 and OR 2.18, 95% CI 1.33-3.57, respectively). In contrast, patients with an increased nevus count and fair or medium skin color were less likely to develop LM than OM (OR 0.93, P < 0.001, 95% CI 0.91-0.94, and OR 0.28, P < 0.001, 95% CI 0.17-0.46, respectively). In univariate analysis, LM exhibited a weaker association with all pigmentary traits than OM. No significant associations were found for atypical nevi count and family history.

We found significant differences in the prevalence of known melanoma risk factors between LM and other melanoma subtypes, which supports the hypothesis of a distinct pathogenetic pathway of LM.