Anatomy of the anterior prostate and extraprostatic space: a contemporary surgical pathology analysis.

Over 25 years ago, McNeal described a model of prostatic zonal anatomy based on autopsy dissections in various planes. As opposed to the cone-shaped organ seen in vivo, radical prostatectomy specimens are typically spherical, owing to tissue contraction at surgical removal and subsequent processing. Sectioning from apex to base yields topography at the Surgical Pathology "sign-out" that may vary from McNeal's descriptions. There are no in depth studies of anterior prostatic anatomic variability, including the periurethral region, peripheral (PZ) and transition (TZ) zones, anterior fibromuscular stroma (AFMS), and anterior extraprostatic space (EPS) using modern prosecting techniques. Detailed analysis of 197 entirely submitted, whole-mounted radical prostatectomy specimens focused on differences in zonal anatomy from apex through base, the relationship of AFMS to PZ and TZ, and the nature of the anterior EPS revealed features that may have significant impact on determination of zonal origin and pathologic staging of anteriorly situated prostate cancer. Among these observations are the predominant nature of the anterior PZ at the apex and the potential for its broad contact with the AFMS at this location, the differing volumes and location of the TZ in prostates with and without benign prostatic hyperplasia, and the composition of the anterior EPS, including adipose tissue, blood vessels, and skeletal muscle at the apex varying to include medium to large smooth muscle bundles at the base.