72235 - Pattern of regional recurrences in patients with trunk melanoma and implications for ultrasound follow-up

Introduction Optimal follow-up of patients with sentinel lymph node (SLN) positive trunk melanoma is uncertain. Completion lymph node dissection (CLND) is no longer indicated and instead these patients are followed by ultrasound examinations. However, exactly which nodal basins to examine has not been established, should it be focused on the positive sentinel node site or all basins indicated by the lymphoscintigraphy? This study aims to describe the patterns of recurrences in patients with trunk melanoma. Method Patients diagnosed with trunk melanoma undergoing wide local excision and SLN biopsy at Sahlgrenska University Hospital, Sweden, between 2017-2021 were retrospectively evaluated in a prospectively held registry. Patients with a positive SLN biopsy did not undergo CLND, instead they were followed with ultrasound every six months for 3 years. Result A total of 261 patients were identified and 39 patients (15%) had a recurrence. Twenty-one (54%) presented with distant recurrences, 12 (31%) with regional nodal recurrences and six (15%) with in-transit metastasis as the first site of recurrence. Of the 261 patients, 55 (21%) had a positive SLN biopsy, and six (11%) of these had a regional nodal recurrence where one recurrence (2%) was outside of the positive SLN basin. Discussion For patients with a positive SLN, the risk of having a first recurrence in a regional nodal basin is 11%. Of these recurrences 83% were in the positive sentinel node basin, making it reasonable to focus the ultrasound examinations on the basin where the positive SLN was identified.