In his editorial “Growth Rate, Early Detection, and Prevention of Melanoma,” Lipsker1 argues that because the actual number of thick melanoma lesions remains stable while that of thin melanoma lesions is increasing rapidly, there are 2 types of melanomas: thick melanomas, whose incidence is stable; and thin melanomas, whose incidence is increasing. He believes that the most challenging task is to identify the risk factors associated with thick, fast-growing melanomas.
Bystryn J. Increasing Ratio of Thin to Thick Melanoma Lesions: Pathogenesis and Early Detection of This Cancer. Arch Dermatol. 2007;143(6):799-816. doi:10.1001/archderm.143.6.804-a