Prostate disorders and cancer: Pathology review

On the urology ward, two people came in. The first is 63-year-old Joseph who complains of difficulty with urination. More specifically, he says he has trouble initiating his stream of urine, and after urination, his bladder still feels full. He also wakes up several times each night feeling the need to urinate. These symptoms have been present for the past few years, but have gradually become worse. Digital rectal examination revealed symmetrically enlarged, smooth, firm, nontender prostate with rubbery or elastic texture. The second is Sam, a 72-year-old African-American individual who comes in with lower back pain that is not relieved by rest or position changes and has been increasing over the past couple of months. He has also noticed recent feelings of fatigue and weight loss, which he attributes to decreased appetite. On further history, he consumes a diet low in fiber and high in saturated fat and red meat. On digital rectal examination, an irregular, hard lump is palpated in the posterior of his prostate. Labs show increased alkaline phosphatase and total PSA levels with decreased free to total PSA ratio.

Both Joseph and Sam have different forms of prostate disorders! Let’s first remind ourselves about physiology real quick. The prostate is a small gland whose job is to secrete an alkaline milky liquid that joins the sperm and the semen. To do that, it sits under the bladder and in front of the rectum. That’s important because when we do digital rectal exam, we’re able to palpate the posterior of the prostate. The urethra goes through the prostate before reaching the penis. And that part of the urethra is called the prostatic urethra.

Now, the prostate can be divided into a few zones and this is high yield! The peripheral zone, which is the outermost posterior section, is the largest of the zones and contain about 70% of the prostate’s glandular tissue. Moving inward, the central zone contains about 25% of the glandular tissue. Last, is the transitional zone, which contains around 5% of the glandular tissue, and is located in the periurethral region of the prostate. The transitional zone gets its name because it contains transitional cells which are also found in the bladder.

At the microscopic level, the prostate is made up of stroma, or connective tissue, and glands. Each of these glands is surrounded by a basement membrane and lined by an outer layer of cuboidal basal cells and an inner ring of luminal columnar cells, which are within the lumen or center of the gland. An important thing to remember is that both the basal cells and luminal cells of the prostate rely on stimulation from androgens for survival, including testosterone which, at the prostate, is converted by the enzyme 5α-reductase into the more potent dihydrotestosterone.