The ABCD system of melanoma detection: a spectrophotometric analysis of the Asymmetry, Border, Color, and Dimension.

BACKGROUND The ABCD (Asymmetry, Border, Color, and Dimension) criteria represent a commonly used clinical guide for the diagnosis of early melanoma. The authors revised these criteria in the light of objective measurements of the features of pigmented skin lesions obtained by telespectrophotometric analysis (TS) in the visible and near-infrared wavelengths. METHODS This study involves a consecutive series of 186 patients with 195 cutaneous pigmented lesions (53 melanomas and 142 nonmelanoma lesions). Each lesion was subjected to TS in vivo, before surgery. For this purpose, the authors used four spectrophotometric parameters that could be closely related to the four criteria of the ABCD guide, namely, roundness (an estimate of how a lesion contour resembles a circle), smoothness (an indicator of the regularity of a lesion border), mean reflectance (the ability of a lesion to diffuse or reflect the incident light), and size (the greatest dimension of a lesion). RESULTS When melanomas and nonmelanoma lesions were compared by univariate analysis, all four spectrophotometric parameters considered proved to be significantly different (P=0.05). Multivariate logistic analysis showed that mean reflectance in the infrared (P < 0.01) and size (P=0.03) were parameters independently associated with melanoma. Melanoma showed lower reflectance and greater size than benign lesions. CONCLUSIONS Information provided by TS substantially validates the importance of the ABCD clinical guide and suggests that color is the most important parameter in discriminating melanoma from nevi. In particular, melanoma appears darker than other pigmented lesions.