Colors in atypical nevi: a computer description reproducing clinical assessment

Atypical nevi share some dermoscopic features with early melanoma, and computer elaboration of digital images could represent a useful support to diagnosis. The aim of our study was to automatically assess colors in atypical nevi, and to compare the data with those referring to clearly benign nevi and melanomas. Dermoscopic images of 459 melanocytic lesions, referring to 76 atypical nevi, 288 clearly benign nevi and 95 melanomas, were acquired by means of a digital videomicroscope (Videocap 100, DS-Medica, Italy) employing a 20-fold magnification. An image analysis program, based on an approach, which shares some similarities with the human perception of colors, was employed. For the evaluation of colors in melanocytic lesion images, the identification of the six main color groups (black, dark brown, light brown, red, white and blue-gray) and the numerical description of color areas were obtained. Black, white and blue-gray were more frequently found in atypical nevi than in clearly benign nevi, but less frequently than in melanomas. Color area values significantly differed between the three groups, showing increasing irregularity in color distribution from benign lesions to atypical nevi and melanomas. The clinical–morphological interpretation of the numerical data, based on the mathematical description of the aspect and distribution of different color areas in different lesion types may contribute to the characterization of atypical nevi and their distinction from melanomas.