The Change of 68Ga-Prostate-Specific Membrane Antigen Uptake in Myeloma After Chemotherapy in a Patient With Multiple Myeloma and Concurrent Prostate Cancer.

A bone lesion in the right calcaneus was found in a 76-year-old man with a history of prostate cancer. Ga-PSMA-11 PET/CT showed multiple PSMA-expressing lytic bone lesions in appendicular skeleton. Biopsy of the lesion in the right calcaneus confirmed plasmacytoma. After several cycles of chemotherapy, the patient was in serologically stringent complete remission. The follow-up PET/CT showed a significant reduction of Ga-PSMA-11 uptake in the previously PSMA-avid bone lesions without morphological changes on CT. The reduction of PSMA expression in myelomas after chemotherapy is suggested to result from the treatment response.