Acquired melanocytic lesions and the decision to excise: Role of color variegation and distribution as assessed by dermoscopy

BACKGROUND. Because melanoma may sometimes be difficult to differentiate from nevi with clinical atypia, many benign lesions also undergo surgical removal. OBJECTIVE. To assess color type and distribution in dermoscopic melanocytic lesion images and to analyze the influence of color parameters on the diagnostic process and the decision to excise. METHODS. Overall, 603 images, referring to 112 melanomas and 491 nevi, were retrospectively subdivided into four groups: clearly benign, follow-up, dermoscopic atypical nevi, and dermoscopic melanomas, according to their dermoscopic aspects. The frequency of color type, number, and asymmetry were evaluated on digital images. RESULTS. With respect to lesions not eligible for excision according to dermoscopy (but excised for cosmetic reasons), those excised with a suspicion of malignancy showed a higher number of colors, whose distribution was also more asymmetric. Moreover, the frequency of the presence of black and blue-gray progressively increased from clearly benign lesions to atypical nevi and dermoscopic melanomas. CONCLUSION. In dermoscopic images, color parameters are essential elements for the diagnosis of atypical nevus, which can be differentiated from both a clearly benign lesion and a melanoma. Furthermore, pigmentation asymmetry and the presence of blue-gray represent the main color features, which should lead to the decision to excise.