MP61-02 DETAILED CADAVERIC ANALYSIS FOR PERIVESICAL LYMPH NODES WITH POTENTIAL IMPLICATIONS IN BLADDER CANCER

INTRODUCTION AND OBJECTIVE: Perivesical lymph nodes were added to the 8 edition of AJCC staging for bladder cancer. In pN+ patients, positive perivesical lymph nodes are associated with even worse overall survival. These nodes are inconsistently evaluated at the time of radical cystectomy (RC) and can be difficult to differentiate from perivesical fat. Currently, no studies have detailed the presence or anatomic location of perivesical lymph nodes. The objective was to provide a detailed anatomic evaluation of perivesical lymph nodes. METHODS: Six unembalmed cadavers with no prior pelvic malignancy or surgery were utilized. An open RC 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. The specimens were fixed in a previously validated lymph node revealing solution for 6 hours. Perivesical tissue dissection in 2 mm slices was performed. Lymph node identification and examination were performed by 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 (2-16 mm). The mean distance from bladder wall was 9 mm (3-15 mm). Ten potential anatomic locations for perivesical nodes were developed: urachal, anterior bladder wall, posterior peritoneum, periprostatic/bladder neck, bilateral peripedicle, bilateral periseminal vesicle, bilateral lateral bladder wall. Nodes were identified in the: Right peripedicle (2 nodes), left lateral bladder wall (2 nodes), posterior peritoneum (1 node), anterior bladder wall (1 node) (Table). On histologic analysis, 4 of the 6 (66%) grossly identified lymph nodes had confirmed lymphoid tissue. CONCLUSIONS: 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 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 RC specimen for perivesical lymph nodes. (Figure Presented).