Figure 1: Melanomagenesis. Melanoma skin cancers originate from melanocytes, sometimes from pre-existing benign lesions called nevi. Melanoma usually develops first in the epidermis, undergoing a radial growth phase before vertically invading the dermis, through the breaking of the basal lamina.The spread occurs through the lymphatic system and/or the blood vessels allowing to neoplastic melanocytes to invade tissues/organs such as the lymph nodes, lung, liver, bones or the brain.