Small Cell Transformation of Metastatic Prostate Adenocarcinoma Diagnosed by Dual-Tracer PET/CT (68Ga-PSMA and 18F-FDG): Potential Clinical Utility in Therapeutic Decision Making and Treatment Monitoring

Transformed small cell carcinoma of the prostate represents a tumor biology distinct from its adenocarcinoma counterpart, and penile metastasis from prostate cancer is a rare phenomenon. Biologic heterogeneity among metastatic lesions in a patient with prostatic adenocarcinoma with SCPCa transformation is presented here. The case report shows the significance of using dual-tracer PET/CT with Ga-68-prostate-specific membrane antigen and F-18-FDG in diagnosing small cell carcinoma of prostate transformation in certain lesions, thereby guiding therapeutic strategies. Furthermore, the value of sequential dual-tracer PET/CT in assessing overall disease status, theranostics, and response to multimodality therapy is illustrated.