Selection of patients with malignant melanoma for pelvic lymph node dissection (PLND) using CT-PET.

Objectives: In melanoma patients with positive pelvic nodes, pelvic lymph node dissection (PLND) to achieve fully resected disease status facilitates adjuvant-dose systemic therapy and avoids higher treatment doses with greater toxicity. This study aimed to test the accuracy of prediction of nodal involvement of the 2010 joint BAPRAS/BAD guidance compared with Positron Emission Tomography (CT-PET).

Methods: A retrospective review was undertaken of 26 melanoma patients undergoing PLND by a single surgeon between July 2012 and July 2020. The indications for performing PLND were in accordance with the 2010 guidance, but this was supplemented by CT-PET in 16/26 patients.

Results: Of the 26 patients undergoing PLND, 10 underwent surgery based upon the 2010 criteria alone and 16 underwent supplementary CT-PET. 17 patients had positive nodes on histology; of these, 13 had a positive CT-PET. Amongst node-negative patients, only one had a false positive CT-PET. CT-PET was 100% sensitive for pelvic nodal disease and 75% specific, with a positive predictive value for nodal involvement of 92%. Of the 10 patients who underwent PLND without CT-PET, only 4 had positive nodes while 6 patients had negative nodes.

Conclusions: The 2010 guidelines remain broad and contributed to negative PLND in a third of our patients (9/26). Hence, the indications for performing PLND need to be revisited. Our series supports PET-CT as being 100% sensitive in the identification of pelvic nodal disease and 75% specific. We recommend that a positive PET-CT should be considered as the primary indication for PLND in melanoma patients.