[Diagnosis of pigmented skin lesions: how to recognize a malignant melanoma].

An accurate answer to the clinical question of whether a pigmented skin lesion has become a malignant melanoma or not is difficult because of the clinical variability of this lesion. Because of the low incidence of 2400 new melanoma cases each year in The Netherlands, a general practitioner only sees one new case every 3-4 years. The best way to distinguish between a benign lesion and a malignant melanoma is the combined use of several criteria, such as in the ABCD-formula: asymmetry, border irregularity, colour variation and a diameter > 6 mm. Dermatoscopical examination, provided that the technique is used by well-trained and experienced physicians, is a valuable adjunct to clinical examination. A pigmented lesion should always be excised if there is not enough convincing evidence to exclude its malignant nature. Histological classification of pigmented lesions may prove difficult because of morphological overlap between benign and malignant melanocytic tumours.