Mills Ch35 Prostate

974

SECTION IX : GenitourinaryTract

FIGURE 35.24  Prostatic acini with basal cells demonstrating little to no cytoplasm and arranged parallel to the basement membrane.

and the stroma by a layer of basal cells. The basal cells are typically elongated and flattened parallel to the basement membrane and have slender dark nuclei and usually little or no discernible cytoplasm (Fig. 35.24) (34). They are typically quite inconspicuous and, in routine preparations may appear incomplete or even absent around individual ducts or acini. Immunohistochemical labeling with high—molecular-weight cytokeratin and/or antibodies to p63 highlights the basal cell population (Fig. 35.25) (35–37). These stains are consistently negative in the cells of invasive malignant glands (36) because basal cells are absent. Basal cells are not myoepithelial cells analogous to those of the breast because, by electron micros- copy, they do not contain muscle filaments (34). In all zones of the prostate, the epithelium con- tains a small population of isolated, randomly scattered endocrine–paracrine cells (38) that are rich in serotonin- containing granules and contain neuron-specific enolase.

FIGURE 35.22  Subsidiary duct and branches in peripheral zone, termi- nating in small rounded acini with undulating borders. Ducts and acini have similar calibers and histologic appearances.

peripheral zone stroma, but blends with the stromas of the preprostatic sphincter and anterior fibromuscular stroma. Stromal distinctions are less evident in older prostates and may be obliterated by disease (32,33). Cytologic Features As with other glandular organs, the secretory cells through- out the prostate are separated from the basement membrane

FIGURE 35.25  Same acini as in Figure 35.24 labeled with a double immunohistochemical stain for 34 β E12 (cytoplasmic) and p63 (nuclear) in basal cells.

FIGURE 35.23  Low-power view of prostatic central zone architecture; large glands with complex luminal infoldings and distinct intraluminal bridges (“Roman arches”).