Lymphatic drainage of prostatic transition and peripheral zones visualized on a three-dimensional workstation

Abstract

Objectives. To determine whether the prostate has lymphatic/lymph node drainage that is not sampled by conventional lymphadenectomy and whether the transition and peripheral zones of the prostate have a different lymphatic drainage, because up to one quarter of lymph-node-negative patients who undergo radical prostatectomy will develop distant metastases. Methods. Ten patients (mean age 62.3 years, range 50 to 76) scheduled for transrectal ultrasound-guided sextant biopsy because of an elevated serum prostate-specific antigen level of 4 to 10 ng/mL and a normal digital rectal examination were included in this study. All patients underwent ultrasound-guided sextant biopsies. Subsequently, an oily contrast medium was injected into the transition zone (group A, n = 5) or peripheral zone (group B, n = 5) of the prostate under transrectal ultrasound guidance and fluoroscopy. Immediately, 1 hour, and 24 hours after the procedure, anteroposterior and lateral radiographs were obtained. In addition, spiral computed tomography of the abdomen was performed 10 minutes after the procedure and analyzed on a three-dimensional workstation. Results. No difference in the lymphatic drainage system between the transition and peripheral zones of the prostate was found. In all patients (n = 10), the lymphatic drainage comprised three major routes: (1) the prostate to the lymph nodes along the lateral bony wall of the pelvis to the angle of internal/external iliac lymph nodes to the common iliac lymph nodes, (2) the prostate to the perineal floor to the pudenda internal lymph nodes to the angle of the internal/external iliac lymph nodes to the common iliac lymph nodes, and (3) the prostate to the sacral lymph nodes. In all 10 patients, main contrast medium enhancement was seen immediately after procedure indicating drainage from the prostate to the lymph nodes along the lateral bony wall of the pelvis. Presacral lymph node enhancement was seen in all patients only in the late (24 hours after contrast injection) radiograph. Conclusions. Our data suggest that the main lymphatic drainage, irrespective of the prostatic region (transition or peripheral zone), runs to the pelvic regions that are mostly removed by standard lymphadenectomy techniques. However, one has to bear in mind that the prostate has some lymphatic drainage that is not covered by standard lymphadenectomy and therefore carries the risk of metastatic tumor spread.