The morphology of the prostatic capsule with particular regard to the posterosuperior region: an anatomical and clinical problem

The composition of the prostatic capsule is important from a clinical point of view, since it is considered to be a barrier against the spread of prostatic tumours. Clinical follow-up demonstrates that apparently intracapsular tumours, particularly in the posterosuperior region of the gland, are frequently understaged at clinical diagnosis. The morphology of the prostatic capsule was studied in 6 cadavers. In each case the prostate was obtained in one block together with the basal portion of the bladder, the seminal vesicles, the anterior wall of the rectum and the periprostatic connective tissue. Part of the material was plastinated, while the remainder was studied using histological and immunohistochemical methods. The prostate was found to be surrounded by connective tissue abundant with smooth muscle cells, and continuous with the stromal septa which subdivide the glandular tissue. A rich network of blood vessels was identifiable. In some regions, particularly in the posterosuperior region, a real capsule was not identifiable. The connective tissue seemed to constitute a continuum between the prostate gland and neighbouring organs, in particular, a connective tissue barrier between the prostate and the seminal vesicles was completely absent. Therefore, due to the absence of a capsular barrier and to the presence of a rich vascular network, a prostatic tumour which begins in the posterior region of the gland should be considered as potentially extracapsular.