[Melanocytoma, an intermediate entity between nevus and melanoma: implications of the WHO classification of melanocytic skin tumours].

The WHO classification of melanocytic skin tumours published in 2018 describes a new classification with nine different pathways based on molecular driver mutations, localization, clinical context and solar damage. The dichotomous concept of benign (nevus) versus malignant (melanoma) is replaced by a gradual concept starting with a benign nevus with progression into low to high grade intermediate melanocytic lesions, called melanocytoma, and ending at melanoma. The current European recommendation is (re-)excision with 2-5mm margin of low grade melanocytoma and with 5-10mm margin of high grade melanocytoma. Low grade melanocytoma needs no follow-up. For high grade melanocytoma a follow-up for at least 5 years every 6 months is recommended. Routine sentinel node procedure is not indicated. If diagnosis melanoma cannot be ruled out the lesions have to be treated as melanoma. Correct classification of a melanocytoma is a diagnostic challenge, but of high importance for therapeutic choices and prognosis.