Mills Ch35 Prostate

967

CHAPTER 35:  Prostate

accomplished in a similar fashion to the prostatic apex; how- ever, some institutions shave a thin section of the most super- ficial muscle fragment(s) surrounding the proximal prostatic urethra and submit this tissue as an en face margin (8). While there is consensus that the junction of the seminal vesicles and the prostate should be sampled, the extent to which the remainder of the seminal vesicle should be submitted is not standardized (9). A reasonable approach may be to take two sections of each seminal vesicle, one at the prostatic junc- tion, as well as a mid-seminal vesicle section to account for both contiguous spread of tumor from the prostatic base, as well as seminal vesicle invasion that occurs in the context of extraprostatic tumor extension. The remaining bulk of the gland is sectioned from apex to base in the anterior–posterior plane at approximately 3-mm intervals (10,11). The resulting complete transverse macrosections are submitted as either full whole mount sections or divided into half or quadrant sections using conventional tissue cassettes. Although there is debate as to the appropriate extent of sampling (8), a mini- mum submission of every other intervening macrosection is often recommended. FIGURE 35.6  Apex of prostate seen grossly after 5-mm thick apical block has been subsectioned parasagittally at 3-mm intervals. Orienta- tion of sections and localization of lesions are easily demonstrated, and cuts through the tissue are nearly perpendicular to the apical surface.

and tissue processing (12,13) is also typical, resulting in arti- factual shortening of the distance from prostatic apex to veru- montanum and everting the posterior periurethral tissue into the urethral space. These effects create an artificial “promon- tory” in the apical portions of the gland (Fig. 35.7) (14). FIGURE 35.7  Distal urethra near the apex. Note the “promontory” or eversion of posterior periurethral tissue into the urethral space. The posterior portion of the semicircular sphincter (see Fig. 35.8) is present as a central muscular column.

Histologic Variation by Anatomic Region Apical One-Third of the Prostate (Apex)

In a surgical pathology specimen sectioned in the anterior–posterior plane, the apical (distal) urethra is located near the center of the section (Fig. 35.8). It is

ANATOMY OF THE PROSTATE GLAND IN SURGICAL PATHOLOGY SPECIMENS

Gross Anatomy In situ operative views of the prostate reveal a cone-shaped organ with its base surrounding the proximal urethral seg- ment and abutting the bladder neck and its apex narrowing around the distal urethral segment as it approaches the uro- genital diaphragm. Surgical manipulation and subsequent detachment of the prostate from native connective tissue leads to superior retraction of the distal (apical) urethra and yields a roughly spherical specimen at the gross dissection bench. Significant tissue shrinkage due to formalin fixation

FIGURE 35.8  Whole mount section from apex of prostate. The urethra and promontory ( P ) are central and proceeding anteriorly, the semi- circular sphincter ( SCS ) and anterior fibromuscular stroma ( AFMS ) are visualized. The posterior, lateral, and anterolateral portions of the apex are composed of peripheral zone ( PZ ) tissue. Most anteriorly, the anterior extraprostatic space ( AEPS ) contains vascular and adipose remnants of the dorsal vascular complex.