Melanoma

Presentation :

Pathophysiology :

• Approximately one half of melanomas harbor a BRAF gene mutation (most commonly V600E), and another 20% have an MEK or NRAS mutation

Diagnostics :

• Nodal metastases are uncommon in thin melanomas, and nodes are typically not assessed if the melanoma has a Breslow depth of less than 0.8 mm and is without ulceration.
• Assessing for lymph node metastasis with lymphatic mapping and sentinel lymph node biopsy is often recommended for intermediate and thicker melanomas.
  • Completion lymph node dissection is no longer routinely performed, as there is no improvement in survival

Treatment :

• Localized Disease
  • Surgical Margins:
    • 1cm margins for lesions <1 mm thick.
    • 1-2cm margin for lesions 1-2 mm thick.
    • 2cm margins for lesions >2 mm thick
• Oligometastatic disease:
  • In patients with one or a very limited number of metastases, surgical excision of all metastatic disease can occasionally produce durable benefit.
• Metastatic disease:
  • In contrast to immunotherapy and targeted therapy, cytotoxic chemotherapy has not been shown to increase survival or to induce durable remissions
• Targeted therapy:
  • Melanomas with BRAF V600E/V600K may respond to oral therapy with the available BRAF/MEK inhibitor combinations (dabrafenib/trametinib; vemurafenib/cobimetinib; encorafenib/binimetinib)
• Immunotherapy:
  • Typically use PD1 inhibitors + CTLA4 Inhibitors
  • However single agent PD1 inhibitors
  • Nivolumab + LAG-3 inhibitors (aka Relatlimab)
  • CTLA4 Inhibitors have greater toxicity than the PD1 inhibitors, and are less effective (20% vs 30-40% response rates).
• UTD Algo:
  • 

Prognosis:

• A high mitotic rate, lymphovascular invasion, and the presence of ulceration are poor prognostic signs.