Diffuse Bone Marrow Involvement of Multiple Myeloma on [ 18 F]PSMA-1007 PET/CT : Is There a Theranostic Potential?

A 71-year-old man presented with chronic anemia (hemoglobin 7.3 g/dL). Further serum analyses showed elevated prostate-specific antigen (13 ng/mL), suggestive of prostate cancer. However, ultrasound-guided transrectal sextant biopsy did not find any evidence of prostate cancer. In order to improve guidance of intended repeated biopsy, [ 18 F]prostate-specific membrane antigen (PSMA) 1007 PET/CT was performed, which showed a solitary lesion with strong PSMA expression in the left peripheral zone in the prostate gland. Surprisingly, also a diffuse bone marrow involvement with predominantly osteolytic lesions was observed. This massive osseous tumor burden was clearly discordant to the only relatively mild elevated prostate-specific antigen. The subsequent bone biopsy revealed multiple myeloma. This case does not only highlight a possible pitfall on PSMA PET/CT, but also raises the question on how far PSMA ligands may offer diagnostic and therapeutic potential in multiple myeloma.