[The atypical nevus: a risk situation?]

Many studies using different approaches and sets of data have concluded that there is a significantly increased risk of malignant melanoma in patients with atypical moles. For clinical identification, the features of ABCD's (Asymmetry, Border, Colour, Dimension) are used, the "ugly duckling" sign (the naevus that does not resemble its "brother naevi"), dermatoscopy and digital approaches. After excision, histologic criteria are used to identify naevi with architectural changes. It has recently been possible to identify allelic losses within known tumour suppressor genes in microdissected atypical moles, using microdissection and loss of heterozygosity analysis, thus providing additional evidence for the concept of the atypical mole as a precursor lesion of melanoma.