title: Occult Metastases in Pelvic Lymphadenectomy Specimens From Patients With Urothelial Carcinoma of the Bladder.
abstract: OBJECTIVE
  To identify occult metastases within lymph nodes (LNs) reported as negative by routine histologic evaluation. In patients with high-grade, muscle-invasive urothelial carcinoma (UC) of the bladder, pelvic lymphadenectomy during radical cystectomy demonstrates a survival advantage, increasing with the number of LNs removed, even if negative for metastatic disease. This finding may potentially be explained by the presence of occult metastases.
  
  
  METHODS
  Radical cystectomy specimens with high-grade UC invading the perivesical tissue and negative LNs (pT3N0) between 2000 and 2014 were reviewed. Five levels were cut for each LN block. Two sections were cut per level: 1 stained for hematoxylin and eosin and 1 for AE1/AE3. Micrometastases were defined as tumor deposits >0.2 mm but <2 mm. Isolated tumor cells were defined as ≤0.2 mm. Medical records and survival data were reviewed.
  
  
  RESULTS
  We identified 21 cases, consisting of 370 lymph nodes. Six of 21 patients (29%) had occult metastases, including 5 occult metastatic UC and 1 occult metastatic prostate adenocarcinoma. There were 10 positive LNs; 2 macrometastases, 2 micrometastases, and 6 with ITCs. Two of 6 patients (33%) had lymphovascular invasion identified in the primary tumor. Kaplan-Meier analysis showed no significant difference in overall survival between the group of patients who remained N0 versus those upstaged due to discovery of occult metastases (P-value = .42).
  
  
  CONCLUSIONS
  In patients with pT3 UC undergoing cystectomy, we demonstrated the presence of occult metastases in 29% of patients. The high percentage of occult metastases present in these cases possibly explains the proven survival advantage of removing "negative" LNs. This finding might also have implications in the histologic evaluation of LNs.
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, Birmingham, AL; Department of Urology, University of Alabama at Birmingham, Birmingham, AL. Electronic address: jgordetsky@uabmc.edu.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Gordetsky
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Briana
authors.initials: B
authors.lastname: Gibson
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Todd M
authors.initials: TM
authors.lastname: Stevens
authors.affiliation: Department of Urology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: J Luke
authors.initials: JL
authors.lastname: Ellenburg
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: William
authors.initials: W
authors.lastname: Grizzle
authors.affiliation: Department of Urology, University of Alabama at Birmingham, Birmingham, AL; Department of Radiology, University of Alabama at Birmingham, Birmingham, AL.
authors.forename: Soroush
authors.initials: S
authors.lastname: Rais-Bahrami
mesh_terms: D000368:Aged; D002295:Carcinoma, Transitional Cell / Q000556:secondary* / Q000601:surgery*; D015653:Cystectomy; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D008297:Male; D010388:Pelvis; D012189:Retrospective Studies; D001743:Urinary Bladder / Q000473:pathology* / Q000601:surgery*