Uncovering Hidden Metastases at Unusual Site

Prostate cancer frequently metastasizes to bones; however, the detection of metastases can be challenging in rare locations. We present the case of a 76-year-old man with metastatic castration-resistant prostate cancer with lymph nodal and skeletal metastases who underwent 177Lu-prostate-specific membrane antigen (PSMA) therapy. Initial 18F-PSMA PET/CT scan acquired until the midthigh failed to identify metastases in the foot, but posttherapy 177Lu-PSMA scan revealed the presence of metastases in the navicular and cuboid bones of the right foot, which is a very rare finding. This case highlights the limitations of standard PSMA PET/CT acquisition protocol and incremental value of whole-body posttherapy scan.