What are the non‑regional lymph node sites for a melanoma originating on the right toe with involvement of the right inguinal lymph node?

Non-Regional Lymph Nodes for Right Toe Melanoma with Right Inguinal Involvement

For a melanoma originating on the right toe with right inguinal lymph node involvement, non-regional nodes include any lymph nodes outside the right inguinal and right pelvic basins—specifically the left inguinal/pelvic nodes, bilateral axillary nodes, cervical/supraclavicular nodes, and any distant nodal sites. 1

Regional vs. Non-Regional Classification

The right inguinal lymph nodes constitute the regional nodal basin for all right lower extremity melanomas, including those arising on the right toe. 1 This is classified as Stage III (regional) disease, not Stage IV (distant metastatic) disease. 1

Regional Nodes for Right Toe Melanoma Include:

• Right superficial inguinal nodes (the primary draining basin) 2
• Right deep inguinal/pelvic nodes (iliac and obturator nodes), particularly when:
  • More than 3 superficial inguinal nodes are involved 2
  • Nodes are clinically positive 2
  • Cloquet's node is positive 2
  • CT or PET imaging demonstrates pelvic involvement 2

Between 30-44% of patients with clinically involved superficial inguinal nodes will have involved pelvic nodes, with risk increasing to 44-90% if Cloquet's node is positive. 2

Non-Regional (Distant) Nodes Include:

• Contralateral (left) inguinal and pelvic nodes 1
• Bilateral axillary nodes 3
• Cervical and supraclavicular nodes 3
• Any other distant nodal basins (mediastinal, retroperitoneal, etc.) 3

Important Caveats About Lymphatic Drainage

Aberrant Drainage Patterns

Lower extremity melanomas typically have highly predictable drainage (approaching 100% predictability to ipsilateral inguinal nodes). 4 However, aberrant sentinel nodes can occur in unusual locations:

• Popliteal nodes may serve as sentinel nodes for distal lower extremity melanomas 5, 6
• Interval nodes (nodes between the primary site and traditional basins) can occur 7, 4
• Approximately 34% of all melanoma patients demonstrate unpredictable drainage patterns, though this is less common for lower extremities 4

Critical point: If lymphoscintigraphy identifies aberrant sentinel nodes (e.g., popliteal), these should be considered regional for that specific patient, and if positive, warrant dissection of that aberrant basin. 6 The definition of "regional" is therefore patient-specific based on actual lymphatic drainage patterns, not just anatomic assumptions. 4, 6

Clinical Implications for Staging

Any involvement of truly non-regional nodes (as defined above) would upstage the patient to Stage IV disease, fundamentally changing prognosis and treatment approach from potentially curative surgery plus adjuvant therapy to systemic treatment for metastatic disease. 1

Mandatory staging workup before lymphadenectomy should include:

• Whole-body PET-CT to identify distant nodal or visceral metastases 1
• Serum LDH level (elevated LDH indicates poorer prognosis) 1
• Pathological confirmation of nodal disease 1