Routine FDG PET‐CT in patients with a high‐risk localized melanoma has a high predictive positive value for nodal disease and high negative predictive value for the presence of distant metastases

Abstract

FDG PET-CT is the superior imaging modality for the detection of visceral metastases (M+) in patients with melanoma. Conflicting evidence exists regarding its role for the initial staging of patients with high risk localized melanoma (large Breslow Thickness (BT) and/or ulceration). To assess the role of routine staging with FDG PET-CT in melanoma patients with localized high risk melanoma. Forty-eight consecutive patients with 1 < BT < 4 mm with ulceration and with BT ≥ 4 mm were staged with PET-CT. PET-CT procedures were performed on a GE Discovery ST® scanner. PET-CT findings for regional nodal status and presence of distant metastatic disease were collected. The gold standard for nodal assessment was pathological examination. The gold standard for M+ was conventional imaging and clinical follow-up, confirmed by biopsy whenever feasible. No patient had a positive PET-CT for M+. Six patients (13%) had a non-conclusive PET-CT; none of them presented with M+ within 6 months. Forty-three patients (90%) had a negative PET-CT, amongst them only one patient (2.5%) presented with M+ within a year. Six patients had FDG-avid lymph nodes in the drainage territory of the primary melanoma, either SLNB or lymph node dissection confirmed metastatic nodal involvement. The predictive positive value of PET for regional node involvement was 100%. FDG PET-CT does not seem to be effective at detecting M+ at baseline staging in patients with high risk localized melanoma. However, it has a high negative predictive value for the presence of M+ at 6 months and a high positive predictive value for nodal involvement.