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WHO Classification of Tumours
Dysplastic nevus


Dysplastic nevi (DN) are solitary or multiple, slightly raised, irregularly pigmented lesions with vague borders and asymmetric shape, usually measuring >0.5 cm in greatest dimension. Histological characteristics include nested and single melanocytes near the tips and sides of elongated rete ridges, stromal reactions and cytologic atypia. Dysplastic nevi may arise anywhere on the body, but are most commonly found on the trunk. In contrast to ordinary moles, dysplastic nevi are also often found on the scalp, buttocks and female breast. Patients may present with one, several or up to hundreds of lesions.
Dysplastic nevi occur sporadically or in a familial setting. Histologically displastic sporadic lesions arise in up to 50% of adult Whites. In patients with the familial form, lesions typically become apparent before the age of 20. Patients with greater numbers of nevi are at greater risk for melanoma. The dysplastic nevi themselves are not considered to be high risk precursors of melanoma, but rather markers indicating an increased risk for melanoma. Histological atypia correlates with melanoma risk

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LeBoit PE, Burg G, Weedon D, Sarasin A (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Skin Tumours
3rd Edition
IARC Press: Lyon 2005