Introduction:

Perivesical lymph nodes were added to the 8^thedition of AJCC staging for bladder cancer. In pN+ patients, positive perivesical lymph nodes are associated with even worse overall survival. Perivesical lymph nodes are inconsistently evaluated at the time of radical cystectomy and can be difficult to differentiate from perivesical fat.  Currently, no studies have detailed the presence or anatomic location of perivesical lymph nodes. 

Methods:

Six un-embalmed cadavers (4 male, 2 female) with no prior pelvic malignancy or surgery were utilized.  An open radical cystectomy was performed on all specimens with wide resection of perivesical tissue and meticulous care to separate the pelvic lymph nodes (e.g. obturator, external iliac) from the specimen.  Due to the amount of perivesical fat, the specimens were fixed in a lymph node revealing solution (95% ethanol, diethyl ether, glacial acetic acid, buffered formalin) for 6 hours.  Perivesical tissue dissection in 2 mm slices was performed.  Lymph node identification and examination were performed grossly and microscopically in conjunction with a board-certified pathologist. Perivesical lymph node size and location in relation to bladder wall was recorded.  

Results:

Gross lymph nodes were identified in the perivesical tissue in 50% (3/6) of the specimens, with a total of 6 lymph nodes identified. The mean lymph node size was 7.5 mm (range 2-16 mm). The mean distance from bladder wall was 9 mm (range 3-15 mm). Ten potential anatomic locations for the perivesical lymph node location were developed: urachal, anterior bladder wall, posterior peritoneum, periprostatic/bladder neck, and bilateral peri-pedicle, bilateral peri-seminal vesicle, bilateral lateral bladder wall.  Lymph nodes were identified in the following locations (Table): Right peripedicle (2 nodes), left lateral bladder wall (2 nodes), posterior peritoneum (1 node), anterior bladder wall (1 node). On histologic analysis, a total of 4 of the 6 (66%) grossly identified lymph nodes had confirmed lymphoid tissue.   

Conclusion:

In a cadaveric model with meticulous dissection, gross and histologically-confirmed lymph nodes were identified in the perivesical space in half of patients.  When present, patients had an average of two lymph nodes that were distributed around the bladder and within 15mm of the bladder wall.  This data, as well as the inclusion of perivesical lymph nodes in AJCC staging, argues for thorough evaluation of the radical cystectomy specimen for perivesical lymph nodes. 

Funding: N/A