Dual-tracer 18F-FDG and 18F-PSMA PET/CT Findings in Metastatic Scrotal Extramammary Paget Disease Initially Suspected as Prostate Cancer

We present dual-tracer 18 F-FDG and 18 F-PSMA (prostate-specific membrane antigen) PET/CT findings in a 75-year-old man with prior scrotal extramammary Paget disease who developed diffuse bone and lymph node lesions. L1 vertebral biopsy initially favored metastatic prostatic acinar adenocarcinoma, but serum prostate-specific antigen was 0.567 ng/mL and prostate biopsies were benign. PET/CT showed intense FDG and PSMA uptake in widespread osseous and nodal lesions, whereas the prostate showed no focal FDG uptake or abnormal PSMA uptake. This discordant imaging pattern, together with clinical and pathologic correlation, supported metastatic scrotal extramammary Paget disease rather than prostate cancer.