Prostatic Zonal AnatomyZonal anatomy has essentially replaced lobar anatomy of the prostate. There are four zones of the prostate (Fig. 62.1): the peripheral zone (PZ), transition zone (TZ), central zone, and the anterior fibromuscular stroma zone. The central zone that surrounds the ejaculatory ducts has marked histologic differences from the PZ. It is the PZ, extending across the entire posterior surface of the gland, that is palpated on rectal examination and is the location of the most prostate cancers. The TZ is the location of benign prostatic hypertrophy. The anterior fibromuscular zone consists of an anterior band of fibromuscular tissue contiguous with bladder muscle and external sphincter. In young men, the PZ is the prominent zone, whereas the TZ becomes the dominant zone with age. It is important to note that there is no “median lobe†zone in this nomenclature, although such a “lobe†may be present in some prostate cancer patients and may have important implications for treatment planning and treatment selection. Histologically, the median lobe arises from the TZ or periurethral stroma, with varying proportions of fibrous, glandular, and muscle tissue.Prostate Physiology
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