Incidence and characteristics of thick second primary melanomas: a study of the German Central Malignant Melanoma Registry.

Background: Fast‐growing melanomas are thought to be responsible for the stable incidence of thick melanomas. It has been suggested that campaigns for early diagnosis are unlikely to have a major impact on prognosis as rapid vertical growth rather than diagnostic delay is the major determinant for thick melanomas. Objective: We investigated the impact of follow‐up examinations on the incidence of thick second primary melanomas (SPMs) and analysed their clinic‐pathologic characteristics. Methods: We analysed a single‐centre cohort of 2253 patients of the German Central Malignant Melanoma Registry with prospectively documented follow‐up examinations. Results: Primary tumour and patient characteristics were well balanced between patients with and without SPMs except for age (median 61 years, interquartile range [IQR] 51–67 vs. 56 years, IQR 43–67; P = 0.005). Metachronous SPMs occurred in 107 patients (4.7% of total) were thinner than the respective first primary melanoma (FPM) (median Breslow thickness of invasive melanomas 0.40 mm, IQR 0.28–0.75 vs. 0.80 mm, IQR 0.50–2.00; P < 0.001) and less often ulcerated (0.9% vs. 15.0%; P < 0.001). Melanomas >2.00 mm occurred in 2.8% of SPMs as compared to 23.4% of FPMs (P < 0.001). Thick SPMs (>1.00 mm; 14.0%) despite close‐meshed follow‐up examinations were frequently associated with atypical clinical presentation and uncommon histopathologic subtypes. One‐third (5/15) of thick SPMs were clinically misdiagnosed as non‐melanocytic lesions, most of them as basal cell carcinomas (n = 4). Conclusions: Regular total body skin examinations enable a highly efficient detection of early‐stage melanomas and reduction of thick melanomas as compared to first primary melanomas. Our data indicate that fast‐growing melanomas without opportunity of early detection are rare and cannot explain the stable incidence of thick melanomas. This highlights the importance of close‐meshed total body skin examinations in patient groups that are at high risk of first or multiple primary melanomas. Linked article: This article is commented on by K. Peris, pp. 13–14 in this issue. To view this article visit https://doi.org/10.1111/jdv.15334. [ABSTRACT FROM AUTHOR]