Staging in thick cutaneous malignant melanoma: A sequenced approach.

Background: Patients with thick cutaneous pT4 malignant melanoma are at high risk for metastatic disease, and optimal staging is poorly defined. This study examines the frequency and modality of pre-operative staging to provoke thought on optimal staging.

Methods: A retrospective study was performed of patients with clinical T4N0 melanoma diagnosed between 2015-2017. The modality (sentinel lymph node biopsy and/or imaging), timing, and findings of staging investigations were assessed.

Results: One hundred thirty-six patients with pT4a or pT4b cutaneous melanoma and clinically negative regional lymph nodes were included. Forty patients underwent no staging. Thirty-six patients underwent pre-operative imaging, and of these, regional or distant disease was identified in seven patients (19%). Another 36 patients underwent upfront sentinel lymph node biopsy concurrently with wide local excision. A positive sentinel lymph node biopsy was found in eight (22%) of these patients, of which two had regional or distant metastatic disease on postoperative imaging. Of 16 who underwent a sentinel lymph node biopsy after negative pre-operative imaging, three had a positive sentinel lymph node biopsy.

Conclusion: Staging is non-standardized and underutilized in patients with thick melanoma. With evolving systemic treatment options, a well-defined approach to staging, with consideration for pre-operative imaging in pT4 patients, is essential for high-risk patients.