What is the appropriate management for a patient with nodular malignant melanoma, 2.9 mm thick, with ulceration, mitotic index of 5/mm^2, and pathologic stage pT3b, showing pleomorphic melanocytes, expansile dermal growth, and tumor-infiltrating lymphocytes, with limited focus suspicious for lymphovascular involvement?

Management of pT3b Nodular Melanoma (2.9 mm, Ulcerated)

This patient requires wide local excision with 2 cm margins and sentinel lymph node biopsy (SLNB), followed by consideration for adjuvant immunotherapy if the sentinel node is positive. 1, 2

Immediate Surgical Management

Wide Local Excision

• Perform wide excision with 2 cm surgical margins for this melanoma >2 mm in Breslow thickness 1
• The 2 cm margin recommendation is based on Level II evidence from randomized trials showing equivalent survival with reduced morbidity compared to wider margins 1, 3
• Margins may need modification only if the lesion involves functionally critical areas (fingers, toes, face, ear), which does not appear to be the case here 1

Sentinel Lymph Node Biopsy (SLNB)

• SLNB is mandatory for this patient given the tumor thickness of 2.9 mm, which carries approximately 20% risk of sentinel node positivity 2, 4
• The presence of ulceration, mitotic index of 5/mm², and suspicious lymphovascular involvement further increases the likelihood of nodal metastases 4, 5
• SLNB should be performed simultaneously with the wide excision to avoid alterations in lymphatic drainage patterns 2, 3
• This procedure must be performed at an experienced center with skilled teams 1, 2

Critical point: The suspicious lymphovascular invasion noted on pathology is a particularly strong predictor of sentinel node positivity—second only to tumor thickness itself on multivariate analysis 5

What NOT to Do

• Do not perform elective complete lymph node dissection without first confirming sentinel node status, as prophylactic lymphadenectomy provides no survival benefit and causes significant morbidity 1, 3
• Do not perform prophylactic lymph node irradiation, as this is not recommended 1

Staging Workup

Imaging Recommendations

• Cross-sectional imaging (CT chest/abdomen/pelvis or PET-CT) is recommended for this stage IIB/III melanoma to evaluate for distant metastases 1, 6, 2
• PET-CT is specifically indicated for melanomas ≥4 mm or stage IIB-IIC and higher to evaluate for distant disease 6, 2
• While this patient's primary is 2.9 mm, the pT3b classification with ulceration, high mitotic rate, and suspicious lymphovascular involvement warrants baseline imaging 6

Laboratory Studies

• Obtain baseline LDH, complete blood count, and liver function tests 1
• Elevated LDH is an important prognostic marker for metastatic disease 1

Adjuvant Therapy Considerations

If Sentinel Node is Positive (Stage III Disease)

• Adjuvant immunotherapy with pembrolizumab or nivolumab should be strongly considered for completely resected stage III melanoma 7, 8
• Pembrolizumab 200 mg IV every 3 weeks for up to 1 year demonstrated statistically significant improvement in recurrence-free survival in the KEYNOTE-054 trial for stage III disease 7
• Nivolumab 480 mg IV every 4 weeks (or 240 mg every 2 weeks) for up to 1 year showed superior recurrence-free survival compared to ipilimumab 10 mg/kg in the CHECKMATE-238 trial 8

If Sentinel Node is Negative (Stage IIB Disease)

• Adjuvant immunotherapy should still be considered given the high-risk features 7, 8
• Pembrolizumab demonstrated significant improvement in recurrence-free survival for stage IIB/IIC melanoma in the KEYNOTE-716 trial 7
• Nivolumab showed significant improvement in recurrence-free survival for stage IIB/IIC melanoma in the CHECKMATE-76K trial 8

High-Risk Pathologic Features in This Case

Several features in this pathology report warrant particular attention:

• Ulceration: Major adverse prognostic factor that upstages the tumor from pT3a to pT3b 1, 9
• Mitotic index of 5/mm²: Independently predicts melanoma-specific survival and should influence adjuvant therapy decisions 9, 5
• Suspicious lymphovascular invasion: Second strongest predictor of sentinel node positivity after tumor thickness 5
• Brisk tumor-infiltrating lymphocytes: Generally a favorable prognostic sign, though does not negate the need for standard management 9, 10

Common Pitfalls to Avoid

• Do not delay SLNB: Must be performed before or simultaneously with wide excision, not as a delayed procedure 2, 3
• Do not assume negative nodes based on favorable features: Despite brisk TILs and absence of microsatellitosis, the combination of thickness, ulceration, and suspicious LVI mandates SLNB 4, 5
• Do not use PET-CT as a substitute for SLNB: PET-CT has very low yield for detecting microscopic nodal disease and cannot replace SLNB for staging 6, 2