The prostatic capsule: does it exist? Its importance in the staging and treatment of prostatic carcinoma.

Pathologic evaluation of tumor extent in a radical prostatectomy specimen for prostatic adenocarcinoma is extremely important in staging and planning further therapy. We studied whole-organ sections of 50 prostate glands, obtained at either radical prostatectomy for adenocarcinoma or cystoprostatectomy for bladder cancer, to evaluate the so-called capsule of the prostate, the prostatic apex, and the surgical margins. The outer surface of the prostatic portion of the specimen was totally inked with different colors for the anterior, posterior, left, and right areas. Cross sections were processed for histologic examination, and the apex (distal 1.5 cm) was amputated and radially sectioned (like a cervical cone). We found that the "capsule" is made up of a band of concentrically placed fibromuscular tissue that is an inseparable component of the prostatic stroma. The outer surface of this tissue gives rise to a few bundles of fibromuscular stroma that penetrate and disappear into the periprostatic connective tissue stroma. The apex is sparse in glandular elements, particularly in the anterior portion, and the outer fibromuscular layer is no longer present. Thus we conclude that the prostate does not have a true capsule, but only an outer fibromuscular band.