MElanoma Research Lymph Node Prediction Implementation National_001

Inclusion Criteria: * Newly diagnosed patients with invasive malignant melanoma of the skin (AJCC 8th edition staging guidelines) elected to undergo sentinel lymph node biopsy per the treating physician's recommendation. * Male or female, age ≥18 years. Exclusion Criteria: * Full primary melanoma pathology report unavailable. * Documented clinically apparent nodal metastases at diagnosis. * Distant metastatic disease (M1a,b,c,d) clinically present at primary diagnosis * Any prior or concurrent primary invasive melanoma mapping to the same draining lymph node basin(s). * Documented history of another (prior or concurrent) primary invasive melanoma of T1b or greater at any site within the last 5 years. * Previous surgery in or radiation therapy to the draining lymph node basin(s) of the current primary melanoma. * Ocular, vulvar, perianal or mucosal melanomas or melanocytic tumors of uncertain malignant potential (MELTUMP) or atypical Spitz tumors.