Background:Malignant melanoma is an aggressive skin cancer that requires accurate staging and prognostication for effective management. Objective:This study aims to evaluate the role of whole-body PET-CT in the staging, prognostication, and clinical decision-making of patients with malignant melanoma, comparing its performance with conventional imaging methods (CT and MRI).Methods:A total of 255 patients diagnosed with malignant melanoma were included in this retrospective study. Patients underwent whole-body PET-CT for staging purposes. The diagnostic accuracy of PET-CT was compared with conventional CT and MRI, and the prognostic value of FDG uptake levels was assessed in relation to overall survival (OS), recurrence-free survival (RFS), and clinical outcomes. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of PET-CT were calculated, and the impact on staging accuracy was evaluated.Results:PET-CT demonstrated superior diagnostic performance with a sensitivity of 92%, specificity of 89%, PPV of 85%, and NPV of 94%. In contrast, CT and MRI showed lower sensitivity and specificity. High FDG uptake (SUV > 10) was associated with a median OS of 18 months and a median RFS of 9 months, while low FDG uptake (SUV < 5) was associated with a median OS of 60 months and a median RFS of 40 months. Staging accuracy was improved with PET-CT, as it correctly downstaged 35 patients (14%) who were overstaged by conventional imaging. Conclusion:Whole-body PET-CT significantly improves the diagnostic accuracy and prognostic assessment of malignant melanoma compared to conventional imaging methods.