Differentiation of Discordant Lesions on Dual-Tracer PET/CT (68Ga-PSMA-11 and18F-FDG) in Prostate Carcinoma: Diagnosis of Second Primary Malignancies

We present 2 cases of metastatic castration-resistant prostate carcinoma with discordant lesions on dual-tracer PET/CT (68Ga-PSMA-11 and 18F-FDG PET/CT), which on subsequent histopathologic evaluation revealed second primary malignancies of combined hepatocellular carcinoma and cholangiocarcinoma and poorly differentiated squamous cell carcinoma. These case illustrations emphasize the need to evaluate discordant lesions on dual-tracer PET/CT, which can lead to early diagnosis of second primary malignancies and thereby can provide better management in these patients.