Multiple primary melanomas in Udine, northeastern Italy: a focus on epidemiology and new risk factors

Patients diagnosed with melanoma are at an elevated risk of developing subsequent primary melanomas. The aim of this study was to assess the prevalence and identify the risk factors associated with multiple primary melanomas (MPMs) in patients referred to the melanoma outpatient service of the Dermatology Unit at the University Hospital of Udine, Italy. We conducted a retrospective analysis on patients with MPMs. For each patient demographic, clinical, and histological data were collected. For each excised melanoma, we recorded Breslow thickness, histological subtype, and anatomical site. A total of 233 patients with melanoma were included in the study, comprising a subgroup of 51 (22%) patients diagnosed with MPM. The mean Breslow thickness for patients with a single melanoma was significantly higher than the Breslow thickness for the first melanoma in the MPM subgroup. Furthermore, a statistically significant decrease in Breslow thickness between the first and second melanomas was observed. In our cohort, patients with MPM had a significantly higher prevalence of nonmelanoma skin cancers (NMSCs) compared with those with a single melanoma. Our study indicates that the prevalence of MPM in the province of Udine is among the highest reported globally. Our finding aligns with the broader literature, which consistently reports lower thickness in second melanoma compared with first melanoma. Finally, the higher prevalence of NMSC in these patients suggests a potential link to chronic ultraviolet exposure.