Not Every PSMA-Expressing Bone Lesion Is Prostate Cancer: Incidental Detection of Metastatic Differentiated Thyroid Carcinoma on Staging 68Ga-PSMA-11 PET/CT

⁶⁸ Ga-PSMA-11-PET/CT is widely used for staging prostate cancer but may also detect nonprostatic malignancies owing to prostate-specific membrane antigen (PSMA) expression in tumor neovasculature. Here, we report a case of a newly diagnosed high-risk prostate adenocarcinoma that underwent staging ⁶⁸ Ga-PSMA-11-PET/CT. In addition to the primary prostatic lesion, PSMA-expressing lesions were identified in the sternum and right thyroid lobe. While skeletal involvement was initially presumed metastatic prostate cancer, further evaluation revealed follicular variant papillary thyroid carcinoma. This case highlights an important diagnostic pitfall and demonstrates the value of PSMA-PET/CT in uncovering clinically occult synchronous malignancies.