Patient Detection of Suspicious Skin Lesions
Malignant melanoma (MM) incidence has been rising for the past six decades, with 87,100 cases diagnosed in the United States in 2017.[1] Over half of melanomas are first detected by patients or their families,[2] with diagnosis of early-stage, thin MM dramatically improving 10-year survival rates.[3] These two facts taken together underscore the importance of patient education to encourage early MM detection.
Since its development in 1985, the ABCD rule (A=asymmetry, B=border irregularity, C=color variegation, D=diameter larger than 6 mm) has been taught as a simple pattern recognition tool to distinguish normal melanocytic nevi from melanomas. This simple rule has been a boon to early MM detection but may fail to pick up small or amelanotic MM, even when adding the "E" for "evolving lesion."[4] In contrast, a newer screening tool instructs patients to compare their cutaneous lesions in search of any outliers—the so-called "ugly duckling" (UD) sign.[5]
The UD rule stems from the notion of the "signature nevus"—that each person forms a characteristic pattern of melanocytic nevi based on genetic determinants such as skin phototype. Hence, by encouraging patients to look for cutaneous lesions that break their typical nevus pattern, the UD sign may show superior sensitivity and/or specificity for MM detection when compared with the more static ABCD rule.
