Brain and Spinal Leptomeningeal Metastases in Prostate Cancer Detected by PSMA PET and MRI Fusion

A 66-year-old man with metastatic castration-resistant prostate adenocarcinoma experienced a rising PSA after multiple systemic therapies and radiation therapy to the cervical and thoracic spine for bone metastases. F-18 piflufolastat (Pylarify) PSMA PET/CT demonstrated widespread metastases, involving bones, lungs, mediastinal and hilar lymph nodes, liver, and intracranial and intraspinal sites. He subsequently developed worsening neurological symptoms. Brain MRI fused with PSMA PET revealed numerous radiotracer-avid scattered leptomeningeal enhancing foci intracranially. Cervical spine MRI fused with PSMA PET demonstrated multifocal radiotracer-avid intradural, extramedullary enhancing lesions. Biopsy of cervical intradural lesions confirmed metastatic prostate carcinoma.