FDG PET/CT imaging suggests lymphoma involving prostate may be more resistant to treatment.

FDG PET imaging is generally not useful for prostate cancer. Nevertheless, incidental intense FDG uptake in the prostate warrants further evaluation to assess for prostatic malignancy. We report a case where intense FDG uptake was incidentally noted in an enlarged prostate on FDG PET/CT scan performed for a large left hilar/mediastinal mass (that was also intensely FDG avid along with several additional FDG-avid lesions elsewhere). Biopsy of the prostate and mediastinal lesions revealed large B-cell non-Hodgkin lymphoma at both sites. Serial FDG PET/CT imaging in this patient revealed that the prostatic lymphomatous lesions showed a slower and incomplete response to chemotherapy compared with other sites of lymphomatous involvement (that showed a rapid and complete response to chemotherapy) in the same patient.