title: The nested variant of urothelial carcinoma: a rare but important bladder neoplasm with aggressive behavior. Three case reports and a review of the literature.
abstract: OBJECTIVE
  To describe our experience with the nested variant of urothelial carcinoma (UC-NV) of the bladder, by characterization of the clinical picture and the prognostic implications of this rare form of bladder neoplasm.
  
  
  METHODS
  Three cases of UC-NV of the bladder treated in our institutions were revised and data compared with previously published case-reports.
  
  
  RESULTS
  Three patients presented with advanced muscle-invasive UC-NV, of which two had lymph node metastasis at cystoprostatectomy. The histopathology in the latter two cases showed the same picture in the lymph node metastasis as in the primary tumor with nests of tumor cells with mild-moderate atypia. In all three cases the tumor involved a ureteric orifice or the bladder neck.
  
  
  CONCLUSIONS
  UC-NV is a rare but important histopathologic entity. It has a poor prognosis. At early stage, tumors might be difficult to differentiate from benign conditions and awareness of the condition is of outermost importance.
authors.affiliation: Department of Urology, Lund University Hospital, SE-221 85, Lund, Sweden. fredrik.lieberg@skane.se
authors.forename: Fredrik
authors.initials: F
authors.lastname: Liedberg
authors.forename: Gunilla
authors.initials: G
authors.lastname: Chebil
authors.forename: Thomas
authors.initials: T
authors.lastname: Davidsson
authors.forename: Virgil
authors.initials: V
authors.lastname: Gadaleanu
authors.forename: Magnus
authors.initials: M
authors.lastname: Grabe
authors.forename: Wiking
authors.initials: W
authors.lastname: Mansson
mesh_terms: D000368:Aged; D002295:Carcinoma, Transitional Cell / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology*; D003937:Diagnosis, Differential; D018450:Disease Progression; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000473:pathology; D009361:Neoplasm Invasiveness; D011379:Prognosis; D017678:Sex Distribution; D001749:Urinary Bladder Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology*; D019459:Urothelium / Q000473:pathology