Mr. jackson, 50 years old, has had discomfort between his scrotum and anus. he also has had some fevers and dysuria. rectal examination is halted by tenderness anteriorly, but no frank mass is palpable. what is the most likely diagnosis?

Prostatitis. The above examination, associated with a history of dysuria, frequency, and incomplete voiding, should lead you to suspect acute prostatitis. Prostate cancer, colon cancer, and polyps should not ordinarily cause systemic symptoms such as fever.