Seminal vesicle invasion in radical prostatectomies: Which is the most common route of invasion?

Introduction Very few studies have been published on seminal vesicle invasion (SVI), and these have obtained conflicting results. The aim of the present investigation was to determine the most frequent of three possible routes of seminal vesicle invasion: (1) extraprostatic extension (EPE) into soft tissue adjacent to the seminal vesicle and then into the wall of the seminal vesicle, (2) invasion via the sheath of the ejaculatory duct, penetrating the muscular wall of the ejaculatory duct or extending up the ejaculatory duct into the seminal vesicle muscle wall, or (3) discontinuous metastases. Materials and methods The surgical specimens of 230 consecutive patients submitted to radical prostatectomy were histologically evaluated by complete embedding and whole-mount processing. Results Of the surgical specimens obtained from 230 patients, 28 (12.17%) showed the presence of either unilateral or bilateral SVI. The routes of SVI in these 28 specimens were: (1) only via the sheath of the ejaculatory duct (0/28; 0%); (2) discontinuous metastases (3/28; 11%), (3) both EPE and via the sheath of the ejaculatory duct (6/28; 21%), and (4) only EPE (19/28; 68%). One-half (14/28; 50%) of the 28 seminal vesicles involved had unilateral invasion and, in most of these cases (42.85%), EPE was unilateral and ipsilateral. Conclusion Our results suggest that the most important and most frequent route of SVI is extraprostatic extension of prostate carcinoma into the soft tissue adjacent to the ipsilateral seminal vesicle and then into the wall of the seminal vesicle.