Editing Benign prostatic hyperplasia (section)

== Pathophysiology ==
[[File:Benign prostate hyperplasia.jpg|thumb|right|Benign prostate hyperplasia]]
As men age, the enzymes [[aromatase]] and [[5-alpha reductase]] increase in activity. These enzymes are responsible for converting androgen hormones into [[estrogen]] and [[dihydrotestosterone]], respectively. This metabolism of androgen hormones leads to a decrease in testosterone but increased levels of DHT and estrogen.

Both the glandular epithelial cells and the stromal cells (including muscular fibers) undergo hyperplasia in BPH.<ref name="Kim2016" /> Most sources agree that of the two tissues, stromal hyperplasia predominates, but the exact ratio of the two is unclear.<ref name=Wasserman>{{cite journal | vauthors = Wasserman NF | title = Benign prostatic hyperplasia: a review and ultrasound classification | journal = Radiologic Clinics of North America | volume = 44 | issue = 5 | pages = 689–710, viii | date = September 2006 | pmid = 17030221 | doi = 10.1016/j.rcl.2006.07.005 }}</ref>{{rp|694}}

Anatomically the median and lateral lobes are usually enlarged, due to their highly glandular composition. The anterior lobe has little in the way of glandular tissue and is seldom enlarged. (Carcinoma of the prostate typically occurs in the posterior lobe – hence the ability to discern an irregular outline per rectal examination). The earliest microscopic signs of BPH usually begin between the age of 30 and 50 years old in the PUG, which is posterior to the proximal urethra.<ref name=Wasserman />{{rp|694}} In BPH, the majority of growth occurs in the transition zone (TZ) of the prostate.<ref name=Wasserman />{{rp|694}} In addition to these two classic areas, the peripheral zone (PZ) is also involved to a lesser extent.<ref name=Wasserman />{{rp|695}} Prostatic cancer typically occurs in the PZ. However, BPH nodules, usually from the TZ are often biopsied anyway to rule out cancer in the TZ.<ref name=Wasserman />{{rp|695}} BPH can be a progressive growth that in rare instances leads to exceptional enlargement.<ref name=Sch2011/> In some males, the prostate enlargement exceeds 200 to 500 grams.<ref name=Sch2011>{{cite journal | vauthors = Ojewola RW, Tijani KH, Fatuga AL, Onyeze CI, Okeke CJ | title = Management of a giant prostatic enlargement: Case report and review of the literature | journal = The Nigerian Postgraduate Medical Journal | volume = 27 | issue = 3 | pages = 242–247 | year = 2020 | pmid = 32687126 | doi = 10.4103/npmj.npmj_69_20 | publisher = Medknow | s2cid = 220652018 | doi-access = free }}</ref> This condition has been defined as giant prostatic hyperplasia (GPH).<ref name=Sch2011/>