PSMA Expression Heterogeneity in Metastatic Prostate Carcinoma: A Case of Discordant Liver Metastases on 68 Ga PSMA PET/CT Showing Uptake on Post-Lu-177 PSMA Therapy Scan.

We report a case of metastatic castration-resistant prostate carcinoma with discordant PSMA (prostate specific membrane antigen) expression- 68 Ga-PSMA PET/CT (positron emission tomography/computed tomography) showed PSMA-avid skeletal metastases but nonavid liver lesions. The patient received 177 Lu-PSMA-617 on compassionate grounds. Post-therapy imaging revealed radiotracer uptake in both skeletal and previously nonavid hepatic metastases, suggesting possible increased lesion amenability. This case highlights the dynamic nature of PSMA expression and the potential role of post-therapy scans in revealing responsive disease not visualized on baseline imaging.