A significant breakthrough in our understanding of the clinical morphology of melanoma was the recognition that many melanomas are asymmetric and have irregular borders, multiple colors, and a diameter greater than 6 mm, which formed the ABCD rule (A for asymmetry, B for border irregularity, C for color variegation, and D for diameter >6 mm), first described in 1985.
3 In addition, it became evident that the history of change and symptoms such as pruritus and bleeding are also important, leading to the addition of the E, standing for evolution in lesion size, shape, or color, to the ABCD rule in 2004.
4,5 Although this knowledge helped detect countless melanomas, many remained elusive by being asymptomatic and lacking any ABCDE features. To address this gap, some proposed adding the “EFG rule” with E standing for elevation, F for firm, and G for growing.
6,7 Others recognized that melanomas often appear as outlier lesions or as different compared with a patient's other, benign, lesions (nevi), a concept known as the ugly duckling sign, described in 1988.
8-10 Attempts were also made to amalgamate the aforementioned observations into the “Do UC” melanoma concept, with the D standing for different, U for uneven, and C for changing.
11 Although all of these rules for examining the skin with the naked eye aided in detecting superficial spreading and nodular melanomas, many still escaped detection. It became clear that examination of the skin required harnessing technology to improve on the ability to detect melanomas and to differentiate them from nevi.