ABSTRACT
Clinical criteria have been defined in an attempt to discriminate between suspect lesions that should undergo nail apparatus biopsy and less suspect ones that can just be followed-up. Suspicious signs are the occurrence of the pigmentation during adulthood, monodactlylic location of the pigmentation, heterogeneity of the pigmentation, and its progressive enlargement. Lesions more likely to be benign are those present since childhood, multiple lesions on several fingers and toes, and stable and homogeneously coloured lesions.
