Benign prostatic hyperplasia. Prostatic carcinoma
Benign prostatic hyperplasia
The prostate is a walnut sized gland between the bladder and the penis. The urethra runs through the center of the prostate from the bladder to the penis letting urine out. Benign prostatic hyperplasia (nodular hyperplasia) is extremely common in elderly men (90%) and is characterized by proliferation of stromal and epithelial cells with enlargement of the gland and commonly urinary obstruction. It is related to excessive androgen-dependent growth, Dihydrotestosterone (DHT) is the ultimate mediator for prostatic growth.
The hyperplasia always occurs in the inner transitional zone of the prostate, and contains many well circumscribed nodules that bulge from the surface. This commonly compresses the urethra and gives our main clinical symptom of lower urinary tract obstruction (hesitancy, frequency, urgency, nocturia etc).
Prostatic carcinoma
This is a common adenocarcinoma of men aged 65-75. Androgens are central to the cancers development, as the cancer will develop in response to androgens (hormone dependent). Hereditary, environment and acquired genetic mutations all also play a role.
Most carcinomas are not visible grossly, more advanced lesions are firm, gray-white lesions with poorly defined margins. Histology shows mostly well differentiated adenocarcinoma that produce well defined glands. With increasing grade we see increased irregularity. Prostatic adenocarcinomas are given a Gleason score to grade them into patterns 1 - 5 (the two most common patterns are added), 1 is the most well differentiated tumours while pattern 5 have no glandular differentiation.
Prostate zones: BPH arises in the transitional zone around the urethra (yellow); most carcinomas arise in the posterior peripheral zone (green).
Image: “Prostate zones” by Mikael Häggström , M.D. Author info - Reusing images - Conflicts of interest: None Mikael Häggström , M.D., CC0, via Wikimedia Commons.
Remember: location explains the clinical picture. BPH grows in the transition zone around the urethra, so it causes urinary obstruction early. About 70% of carcinomas arise in the peripheral zone (posterior), so they are often felt as a hard nodule on rectal examination and cause urinary symptoms only late.
Prostatic carcinomas can be identified on routine screening and observation of increased prostate-specific antigen (PSA).