What AJCC 8th edition stage corresponds to a pathological T4b, Nx melanoma of the right toe?

Staging of pT4bNx Melanoma

A pT4b melanoma with unknown nodal status (Nx) is classified as clinical Stage IIC according to AJCC 8th edition staging criteria. 1

Understanding the Staging Components

T4b Classification

• T4b indicates a melanoma with Breslow thickness >4.0 mm with ulceration present 1
• This represents the highest T category in the AJCC staging system and carries significant prognostic implications 1

Nx Designation and Clinical Staging

• Nx means the nodal status has not been pathologically assessed (no sentinel lymph node biopsy or clinical nodal evaluation performed) 1
• When nodal status is unknown or not assessed, clinical staging defaults to N0 (clinically node-negative) for staging purposes 1
• The NCCN staging table explicitly shows that T4b + N0 = Stage IIC 1

Critical Staging Principles

Why This Matters Clinically

• Stage IIC melanoma has a worse prognosis than some Stage III disease, with 5-year melanoma-specific survival of approximately 75% 1
• The presence of ulceration in T4 melanomas significantly worsens prognosis compared to T4a (non-ulcerated) lesions 1
• Sentinel lymph node biopsy is strongly recommended for all T4 melanomas to accurately determine true pathologic stage 1

Prognostic Significance of Missing Nodal Information

• Approximately 47% of T4 melanoma patients have positive sentinel lymph nodes when biopsied 2
• SLN status is the most significant prognostic factor in T4 melanoma, with 5-year overall survival of 80% for SLN-negative versus 47% for SLN-positive patients 2
• Patients with T4b melanoma and negative SLN have significantly better outcomes (5-year melanoma-specific survival 71-80%) compared to those with positive nodes 3, 2

Common Pitfalls to Avoid

Staging Errors

• Do not assume Stage III simply because the tumor is thick—without documented nodal involvement, it remains Stage II 1
• Do not confuse clinical staging (cStage) with pathologic staging (pStage)—the "p" prefix indicates pathologic assessment of the primary tumor, but Nx means nodes were not pathologically assessed 1

Management Implications

• This patient should undergo sentinel lymph node biopsy unless significant comorbidities preclude it, as nodal status dramatically affects prognosis and treatment decisions 1
• If SLNB reveals positive nodes, the stage would be reclassified to Stage IIID (T4b with any nodal involvement) 1
• Adjuvant immunotherapy with anti-PD-1 agents (pembrolizumab or nivolumab) is indicated for Stage IIC melanoma following complete resection 4

Anatomic Considerations for Toe Melanoma

• Acral melanomas (including toe lesions) may have different mutation profiles than cutaneous melanomas, with higher rates of KIT mutations 5
• Wide local excision margins may need modification for functional preservation on the toe, though this should not compromise oncologic adequacy 6
• Subungual melanomas typically require amputation of the affected digit 7