How do cancerous moles spread on your skin?

Skin and Lymph Nodes. Usually through skin(directly spreading through epidermis and dermis), blood vessels and lymphatic channel(which ended up showing at neck, axillae, groins, etc.).
Local growth. A cancerous mole is a changed mole or a melanoma. Melanomas enlarge or spread by extension deeper into the skin more advanced cancers can then spread by small blood vessels or lymphatics. These lesions must be properly evaluated and removed as early as possible.