68Ga-DOTATOC and 68Ga-PSMA PET/CT Unmasked a Case of Prostate Cancer With Neuroendocrine Differentiation.

A bedridden 90-year-old man with fever and elevated prostate-specific antigen (PSA) (49 ng/mL) was referred for differentiation between infection and tumor. F-FDG PET/CT was negative for infection, but Ga-PSMA PET/CT showed multiple lesions in prostate gland with infiltration to bladder wall and seminal vesicle, consistent with locally advanced prostate cancer. The lesion with the highest Ga-PSMA uptake was strongly avid for Ga-DOTATOC, suggesting neuroendocrine tumor differentiation. After hormonal therapy, PSA normalized, but chromogranin-A increased (from 251 to 398 ng/mL), inferring progression of neuroendocrine tumor differentiation. Advanced prostate cancer may require investigation for pathological neuroendocrine transformation, although PSA may suggest improvement.