title: Low-grade papillary urothelial carcinoma of the urinary bladder: a clinicopathologic analysis of a post-World Health Organization/International Society of Urological Pathology classification cohort from a single academic center.
abstract: BACKGROUND
  Few large cohort studies have addressed outcome in patients with noninvasive low-grade papillary urothelial carcinoma (LG-UrCa) following implementation of the 2004 World Health Organization/International Society of Urological Pathology (WHO/ISUP) consensus classification.
  
  
  OBJECTIVE
  To evaluate our cohort of LG-UrCa cases classified according to 2004 WHO/ISUP to reassess outcome and interobserver agreement.
  
  
  METHODS
  Files were searched for all patients diagnosed with LG-UrCa between 1998 and 2008. All sections were reevaluated for accuracy of classification.
  
  
  RESULTS
  A total of 112 cases initially diagnosed as LG-UrCa were identified. Of those, 8 of 55 cases (15%) initially diagnosed by nonurologic pathologists were reclassified as high-grade papillary urothelial carcinoma and were excluded. The mean length of follow-up was 40.1 months (range, 2-113 months). Tumor recurrence was encountered in 56 of 104 patients (53.8%), including 37 (35.6%) with LG-UrCa or lower-grade tumors and 19 (18.3%) with high-grade papillary urothelial carcinoma. Of the 19 patients demonstrating grade progression, 7 (37%) also developed stage progression (invasive carcinoma, n = 5; metastatic carcinoma, n = 2). Seven patients eventually underwent radical cystectomy. None of the 104 patients died of bladder cancer. The mean number of recurrence episodes was 3.11. The mean durations of time to first recurrence and time to grade progression were 13.9 months and 25.1 months, respectively. The mean size of initial tumors was 1.73 cm. There was no significant correlation between tumor size, patient age, sex, or smoking history and the likelihood for recurrence or grade progression. A significantly higher rate of recurrence was seen in patients with multiple tumors at initial diagnosis (P = .04).
  
  
  CONCLUSIONS
  A tendency to underdiagnose high-grade papillary urothelial carcinoma continues to exist. More than half (53.8%) of patients with LG-UrCa developed recurrence, with an 18.3% incidence of grade progression and a 6.7% incidence of stage progression. Patients with multiple initial tumors had significantly higher risk of developing recurrence.
authors.affiliation: Department of Pathology, Johns Hopkins University, Baltimore, Maryland, USA.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyamoto
authors.forename: Fadi
authors.initials: F
authors.lastname: Brimo
authors.forename: Luciana
authors.initials: L
authors.lastname: Schultz
authors.forename: Huihui
authors.initials: H
authors.lastname: Ye
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Miller
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Fajardo
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Lee
authors.forename: Jonathan I
authors.initials: JI
authors.lastname: Epstein
authors.forename: George J
authors.initials: GJ
authors.lastname: Netto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000473:pathology*; D002295:Carcinoma, Transitional Cell / Q000556:secondary*; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local; D012955:Societies, Medical; D001749:Urinary Bladder Neoplasms / Q000473:pathology*; D014944:World Health Organization