Incidentalomas of the prostate detected by 18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography

Prostate incidentalomas are prostatic lesions suspicious for cancer discovered by imaging patients without a known history of prostatic cancer (CaP) for other reasons. 18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG PET) is used to diagnose, stage and assess response to treatment for numerous cancers, but it is not routinely used for CaP. We aimed to determine the rate of detection of prostate incidentalomas in patients undergoing FDG PET and to evaluate the natural history of these lesions. Methods: A retrospective review was conducted of all FDG PET scans performed between 2005 and 2017 at a single institution. Patients were selected who had prostatic uptake without a history of prostate cancer. Clinical data were collected from electronic medical records to determine how the prostate incidentalomas were further evaluated and define the rate of malignancy. Results: A prostate incidentaloma was identified in 309 (1.0%) of 31 019 FDG PET scans performed on men. A prostate-specific antigen (PSA) test was obtained in 40.1% of patients within six months of prostate incidentaloma detection. Six patients underwent a multiparametric magnetic resonance imaging (MRI) of the prostate, which identified CaP in one case. Overall, CaP was diagnosed in 33 cases, representing 10.7% of the prostate incidentalomas and 0.1% of the scanned patients. CaP was intermediate- or high-risk in 27 (8.7%) of the prostate incidentalomas. Conclusions: Incidental lesions detected in the prostate by FDG PET may represent clinically significant CaP. Referral to a urologist for further evaluation should be considered if the patient is otherwise in reasonable health.