Multiple Solitary Plasmacytomas With Multifocal Bone Involvement Diagnosed With 68Ga-Prostate-Specific Membrane Antigen PET/CT.

A 63-year-old man with elevated prostate-specific antigen serum levels and enlarged prostate gland underwent ultrasound-guided transrectal biopsy, which did not reveal any evidence of malignancy. In order to help guidance of repeat biopsy, Ga-prostate-specific membrane antigen-targeted ligand PET (PSMA PET/CT) was ordered. PET/CT scan showed no abnormal PSMA expression within the prostate gland. There were, however, multiple PSMA-expressing osteolytic lesions throughout the axial skeleton. Bone lesion biopsy obtained for final workup revealed multiple solitary plasmacytomas with multifocal bone involvement. This rare case highlights the utility of PSMA PET/CT in diagnosing nonprostate malignancies.