What is the treatment and prognosis for a 65-year-old male with a melanoma on the scalp, Breslow thickness (tumor thickness measured in millimeters) 1mm and Clark level (tumor invasion level) 3?

Treatment and Prognosis of 1mm Scalp Melanoma in a 65-Year-Old Male

For this 1mm Breslow thickness melanoma, perform wide local excision with 1 cm surgical margins and strongly consider sentinel lymph node biopsy for accurate staging. 1, 2

Surgical Management

Wide local excision with 1 cm margins is the standard of care for melanomas ≤1 mm in Breslow thickness. 3, 1, 2 This recommendation is supported by Category 1 evidence from multiple randomized trials demonstrating that 1 cm margins result in similar rates of local recurrence, disease-free survival, and overall survival compared to wider margins for thin melanomas. 1

• The initial biopsy site should be re-excised with these margins measured from the edge of the original lesion or biopsy scar. 3, 1
• For scalp melanomas specifically, achieving adequate margins may require careful planning due to anatomic constraints, but the 1 cm margin should still be the goal. 3, 1
• Primary closure is often feasible, though skin grafting or local flaps may be necessary depending on location and tissue availability. 3

Critical Consideration for Clark Level 3

The Clark level 3 designation (invasion into the papillary-reticular dermal interface) adds prognostic significance for this thin melanoma. 3 For melanomas with Breslow thickness less than 1 mm, Clark's level has independent prognostic value and should influence your decision regarding sentinel lymph node biopsy. 3

Sentinel Lymph Node Biopsy Decision

Sentinel lymph node biopsy (SLNB) should be strongly considered for this patient despite the 1mm thickness, given the Clark level 3 invasion. 3, 4

• For melanomas 0.75-1.0 mm thick, approximately 6.2% of patients have positive sentinel nodes. 3
• Clark level is one of the factors predicting increased probability of positive sentinel nodes in thin melanomas. 3
• SLNB provides critical staging information that guides eligibility for adjuvant therapy and defines prognosis. 4
• The procedure should only be performed by experienced teams with expertise in lymphatic mapping. 2
• Patients should understand that SLNB is primarily a staging procedure with approximately 5% surgical morbidity. 4

Do not perform elective complete lymph node dissection without evidence of nodal involvement. 3, 2 This is associated with significant morbidity without survival benefit. 2

Prognosis

The prognosis for this patient is generally favorable, with the Breslow thickness being the most powerful prognostic factor. 3

• For melanomas ≤1 mm, 5-year survival rates typically exceed 90-95%. 3
• The Clark level 3 designation indicates slightly higher risk than Clark level 2 lesions of similar thickness. 3
• Scalp location may confer slightly worse prognosis compared to extremity melanomas, though this is less significant than Breslow thickness. 3
• Age (65 years) and male sex are additional prognostic factors that slightly worsen prognosis, though their value is low compared to Breslow thickness. 3

If Sentinel Node is Positive

If SLNB reveals micrometastases, the number of involved nodes becomes the most important prognostic factor. 3 In this scenario:

• Completion lymph node dissection should be considered, though recent evidence suggests observation may be reasonable in selected cases. 4, 2
• The patient should be evaluated for adjuvant systemic therapy clinical trials. 4
• Prognosis would be significantly altered, with 5-year survival dropping substantially based on nodal burden. 3

Follow-Up Strategy

Regular clinical follow-up is the primary surveillance strategy; routine imaging is not recommended for asymptomatic patients. 4

• Perform thorough skin and lymph node examinations at regular intervals. 3
• Imaging studies should only be obtained to evaluate specific signs or symptoms of potential metastasis. 4
• If SLNB is not performed or unsuccessful, ultrasound surveillance of the regional lymph node basin should be considered. 4

Common Pitfalls to Avoid

Do not use inadequate surgical margins (<1 cm) for this melanoma. 1, 2 Even though it is exactly 1mm thick, the 1 cm margin is the minimum acceptable standard. 1

Do not overlook the significance of Clark level 3 in decision-making about SLNB. 3 This feature increases the likelihood of nodal involvement beyond what thickness alone would predict. 3

Do not perform routine prophylactic lymph node dissection. 1, 2 This outdated practice increases morbidity without survival benefit. 2

Ensure meticulous pathologic examination if SLNB is performed. 3 Serial sectioning and immunohistochemical staining are mandatory, as even scattered clusters of melanoma cells in a sentinel node are clinically relevant. 3