Amyloidosis of the seminal vesicles simulating tumor invasion of prostatic carcinoma on endorectal MR images

Amyloid deposits within the seminal vesicles are a common finding at autopsy. The incidence increases with age. Amyloid deposits can mimic tumor extension into the seminal vesicles due to prostate or bladder cancer on T2-weighted MR images. We describe a case of seminal vesicle amyloidosis demonstrating the MR appearance and the characteristic pathologic findings. Recognizing seminal vesicle amyloidosis may prevent overstaging prostate cancer on MR images.