Cytokeratin 34 beta E-12 immunoreactivity in benign prostatic acini - Quantitation, pattern assessment, and electron microscopic study

Because of the widespread use of keratin 34 beta E-12 to assist in the dist inction between benign acini and malignant glands, the lack of immunoreacti vity Of benign prostatic acini are important issues. We studied midprostate whole-mount sections from 21 low-volume adenocarcinoma radical prostatecto my specimens with keratin 34 beta E-12. We marked out benign 0.25-cm(2) are as in the peripheral and transition zones and counted the number of small a cini immunoreactive with keratin 34 beta E-12 to a total of 50 acini within each area. Small benign acini from nonatrophic peripheral zone lobules of 3 prostate specimens were examined by electron microscopy. The median numbe r of immunoreactive acini in each region was 49. The nonreactive acini were always the most peripheral acini in a lobule, a small cluster of outpouche d acini furthest from a large duct, or the terminal end of a large duct. Mo re proximal acini had a discontinuous pattern of immunoreactivity Electron microscopy showed occasional acini with luminal cells abutting the basement membrane, without the interposition of basal cell cytoplasm, and other aci ni with extremely attenuated basal cell cytoplasmic processes containing sp arse bundles of intermediate filaments. The basal cell layer becomes attenu ated toward the periphery of some lobules and duct outpouchings, producing nonreactive acini adjacent to discontinuously reactive acini.