You are performing a routine physical on a 70 year old retired banker. On exam of the prostate you palpate a mass that is 1cm in diameter, hard, and nontender. The patient has had a 6 month history of fatigue. He denies weight loss, or night sweats. What is your most likely diagnosis?
a) benign prostatic hyperplasia
b) internal hemorrhoid
c) prostatitis
d) prostate cancer