Luminal contents of benign and malignant prostatic glands: correspondence to altered secretory mechanisms.

Recent changes in tissue fixation strategy, using glutaraldehyde, have clarified the secretory mechanisms of the normal prostate identifying cytoplasmic prostatic secretory granules, structures not preserved by formalin fixation. This normal secretory mechanism was absent in most adenocarcinomas, depicting an important metabolic change in transformed prostate cells. The current study further investigates differences between benign and malignant prostate secretion and relates them to the production of corpora amylacea by benign glands and crystalloids or mucin by cancer. In all normal prostate cells examined (6 cases), prostate secretory granules (PSG) were approximately 1-microm, brightly eosinophilic granules filling the cytoplasm of secretory cells and released in packets by a specialized apocrine cell structure. After apocrine decapitation and luminal dispersal, some of the cytoplasmic and PSG remnants condensed to form eosinophilic bodies (EB) with a glycoprotein rim and central protein core. EB were observed adsorbing and layering onto the surface of prostatic corpora amylacea representing their chief mode of enlargement. Biochemical analysis and x-ray diffraction studies confirmed sulfated glycosaminoglycans of similar structure as the main constituent of both PSG and corpora amylacea. Peripheral zone amphiphilic "dark cell" carcinoma (9 cases) contained almost no PSG, and showed neither apical decapitation nor EB formation, but mucin secretion was frequently detected. Crystalloids that share the same staining characteristics and sulfur content as PSG and corpora amylacea were identified in 3 selected "clear cell" carcinomas, all of which showed at least focal PSG secretion. The recognition of these differing secretory mechanisms and their deviation from normal further defines the histological criteria and spectrum of prostate malignancy.