title: Nuclear size measurement for distinguishing urothelial carcinomas from reactive urothelium on tissue sections.
abstract: BACKGROUND
  Pathological diagnosis of urothelial carcinoma (UC) is primarily based on cytological atypia. It has previously been shown that high-grade (HG) UC, particularly UC in situ cells (CIS), can be over five times the size of a lymphocyte. However, this has not been demonstrated in comparison to reactive urothelium. The objective of this study was to empirically compare the difference in nuclear size of UC cells with reactive urothelial cells.
  
  
  METHODS
  Using CellSens imaging software, we measured urothelial nuclear length (l) and width (w) on digital images of H&E sections. The area (a) of a nucleus was calculated based on the oval shape of most urothelial cells. Lymphocytes were measured to calculate normalized urothelial linear and area ratios.
  
  
  RESULTS
  A total of 1085 urothelial cell nuclei from 60 cases were measured from reactive urothelium, low grade (LG) UC, HG UC and CIS. CIS nuclei were found to have an a 2.75 times larger than reactive nuclei (p < 0.001). A nuclear size cut-off of 11 um for l and 7 um for w was found to be sensitive [98.09 % (95 % CI: 95.60-99.38 %) and 89.31 % (95 % CI: 83.6-91.82 %) for l and w, respectively] and specific [92.60 % (95 % CI: 87.13-95.82 %) and 85.71 % (95 % CI: 79.49-90.63 %) for l and w, respectively] for distinguishing CIS from reactive atypia.
  
  
  CONCLUSIONS
  Nuclear morphometry can be used to differentiate CIS from reactive atypia. A l over 11 um and a w over 7 um and is highly sensitive and specific for CIS compared to reactive urothelium. This difference in nuclear size may be used as a tool for differentiating the flat urothelial lesions from reactive urothelium in daily practice.
authors.affiliation: Department of Pathology, Northwestern University Feinberg School of Medicine, 251 E. Huron St., Feinberg 5-705, Chicago, IL, 60611, USA.
authors.forename: Kate
authors.initials: K
authors.lastname: Poropatich
authors.affiliation: Northwestern University, Evanston, IL, USA.
authors.forename: Jason C
authors.initials: JC
authors.lastname: Yang
authors.affiliation: Department of Pathology, Northwestern University Feinberg School of Medicine, 251 E. Huron St., Feinberg 5-705, Chicago, IL, 60611, USA.
authors.forename: Rajen
authors.initials: R
authors.lastname: Goyal
authors.affiliation: Robert H Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Vamsi
authors.initials: V
authors.lastname: Parini
authors.affiliation: Department of Pathology, Northwestern University Feinberg School of Medicine, 251 E. Huron St., Feinberg 5-705, Chicago, IL, 60611, USA. xyang@northwestern.edu.|Robert H Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA. xyang@northwestern.edu.
authors.forename: Ximing J
authors.initials: XJ
authors.lastname: Yang
mesh_terms: D002278:Carcinoma in Situ / Q000175:diagnosis*; D002295:Carcinoma, Transitional Cell / Q000175:diagnosis*; D002467:Cell Nucleus / Q000473:pathology* / Q000648:ultrastructure; D003937:Diagnosis, Differential; D006801:Humans; D008214:Lymphocytes / Q000473:pathology; D012984:Software; D014571:Urologic Neoplasms / Q000175:diagnosis*; D019459:Urothelium / Q000473:pathology*
keywords: High-grade urothelial carcinoma (HG UC); Low-grade urothelial carcinoma (LG UC); Nucleomegaly; Reactive urothelial atypia; Urothelial carcinoma in situ (CIS)