The purpose of this registry is to collect data in order to discover whether melanoma patients with minimal SN tumor burden should undergo a complete lymph node dissection (CLND) or not.

Currently, if a patient has a positive (or metastatic) SN, this patient will be offered a CLND, which is a surgical intervention aiming to remove all lymph nodes from the same nodal basin as the SN. However, if the positive (or metastatic) SN is only minimally involved, some centers and/or countries do not offer a CLND routinely. As a matter of fact, the CLND procedure does not increase survival for patients with a minimal SN tumor burden, but can add prognostic information, potentially useful in the subsequent decision-making process. However, this is a surgical operation for the patient, which might be accompanied by significant side effects. Moreover, only approximately 20% of patients with a metastatic SN have further lymph node metastases in the same basin, which means that about 4 patients out of 5 will not benefit from a CLND. Thus, there is an urgent need to identify which SN positive patients could be safely spared from a CLND. It has been demonstrated that breast cancer patients with minimal SN tumor burden can be safely managed with nodal observation only, without performing a CLND. There is evidence that the same situation exists in melanoma as well, but this needs to be validated and this is why we are conducting this registry.

The results of this registry will be crucial to establish an accepted standard of care (CLND or nodal observation) for melanoma patients with minimal SN tumor burden.

Inclusion Criteria:

• 18 years of age or older
• Histological evidence of primary cutaneous melanoma
• Metastases solely confined within the SN:
• in the sub-capsular space (with no parenchymal infiltration) and with a maximum diameter of the largest metastasis not greater than 0.4 mm or
• regardless of the site, any sub-micrometastasis with a maximum diameter not greater than 0.1 mm If there is more than 1 metastatic SN, the patient will be still eligible provided that all involved SN have minimal tumor burden, regardless of the amount of positive SNs and the interested basin

Exclusion Criteria:

• No history of any other malignancy within the past 5 years, except for non-melanoma skin cancer (Basal Cell Carcinomas or Squamous Cell Carcinomas) and in situ cervical cancer
• Absence of any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule; those conditions should be discussed with the patient before registration in the trial -

Patients with minimal SN tumor burden