Neurosonology Practice Exam

Benign prostatic hyperplasia most often originates in the transitional zone, the inner portion of the prostate that surrounds the proximal urethra. As men age, this zone undergoes hyperplasia of both the glandular and stromal components, leading to enlargement that encroaches on the urethral lumen. The result is obstructive urinary symptoms, such as hesitancy, weak stream, and nocturia, due to reduced patency of the urethra at the level where the bladder outlet is narrowed. This site is distinct from where other prostatic conditions arise. The peripheral zone—forming the outer rim of the gland—is where most prostate cancers develop, not BPH. The central zone surrounds the ejaculatory ducts and is less commonly involved in BPH. The anterior fibromuscular stroma has little glandular tissue, so it is not a typical origin for hyperplasia. Hence, the origin of BPH is the transitional zone.