The spectrum of melanocytic lesions: From examples to biologically relevant conditions

The progression of melanocytic lesions and the prediction of their behavior depends on a careful assessment of essential pathological features like symmetry and maturation (both morphological and functional). Both the tumorigenic and mitogenic activity are also paramount in the prediction of metastatic potential and represent the essential elements to define the growth phase of melanocytic lesions and the transition and classes used to categorize them. All these elements are interconnected and closely related with the molecular pathways and groups for both junctional and dermal compartments. All these aspects are discussed from typical cases, along with the main differential diagnosis.