When melanoma spreads, it does so invariably by the lymphatic system which drains to the regional lymph nodes. Uncommonly, melanoma can become trapped in the lymphatic vessels and grow to cause tumour nodules in the skin called in-transit disease which has its own highly specialised treament methods and outcomes.
Wide excision and excision are biopsies explained
Lymphadenectomy surgery is used when melanoma spreads to the lymphatics, in an attempt to remove cancerous nodes and stem further spread. The procedure is sometimes used diagnostically.