Metamorphosis of melanoma. Trends in size and thickness of cutaneous melanoma over one decade at the Istituto Nazionale Tumori, Milan

AIMS AND BACKGROUND: Messages about the description of the clinical features of cutaneous melanoma (CM) have remained unchanged since 1985, when the ABCD (Asymmetry, Border irregularity, Color variegation, Diameter >6 mm) rule for melanoma detection was formulated. Given the significant shift to the diagnosis of earlier-stage CMs over the past decades, it is reasonable to think that also the clinical aspects of the disease might have changed. The aim of this study was to examine trends in the presentation of CM over the last decade at our Institution, focusing on two characteristics of the disease: size and thickness. METHODS: A retrospective study was conducted including 1,603 primary invasive CMs seen and treated at the Unit for Melanoma Detection at our Institute between January 1997 and December 2006. RESULTS: The results showed a trend towards smaller CMs, with a difference of 3 mm in median size from the beginning to the end of the period. Detection of small (< or =6 mm) CMs increased at a rate of about 1.5% per year, with a current ratio of 25% with respect to all CMs. Thickness remained substantially unchanged over time. CONCLUSIONS: Physicians must be aware that the characteristics of melanoma have undergone a metamorphosis over the years and the ABCD signs cannot be relied on for adequate sensitivity to further the early detection of CM