title: Cytological findings of the micropapillary variant of urothelial carcinoma: a comparison with typical high-grade urothelial carcinoma.
abstract: BACKGROUND
  Micropapillary variant of urothelial carcinoma (MPUC) showed distinct pathologic features and aggressive behavior. The cytologic findings of MPUC are still indistinct. In this study, we evaluated the cytological findings of MPUC compared with those of high-grade urothelial carcinoma (HGUC).
  
  
  METHODS
  The voided urine cytology of 8 cases of MPUC and 8 cases of HGUC was reviewed. Following cytological parameters were evaluated: cellularity, background, number of small, tight papillary clusters, small acinar structure, scattered single cells, cytoplasmic features, nuclear-to-cytoplasmic ratio, nuclear pleomorphism, nuclear membrane irregularity, hyperchromasia, chromatin pattern and nucleoli.
  
  
  RESULTS
  Compared to that of HGUC, cytology of MPUC showed large numbers of small, tight papillary clusters, small acinar structure, few numbers of single cells, and hyperchromatic nuclei. Other parameters were similar between the two groups; both groups showed similar cellularity, dense or vacuolated cytoplasm, moderate to severe nuclear pleomorphism, irregular nuclear membrane, coarse granular chromatin, and small and prominent nucleoli.
  
  
  CONCLUSIONS
  The urine cytology of MPUCs showed smaller and tighter papillary cell clusters, more small acinar structures, fewer numbers of scattered single cells, and more hyperchromatic nuclei than that of HGUC. These features can help to distinguish MPUC and HGUC and offer an early cytological diagnosis of MPUC.
authors.affiliation: Department of Pathology, Inha University Hospital, Inha University College of Medicine, Incheon, Korea.
authors.forename: Kyu-Ho
authors.initials: KH
authors.lastname: Kim
authors.forename: Chang-Hwan
authors.initials: CH
authors.lastname: Choi
authors.forename: Jee-Young
authors.initials: JY
authors.lastname: Han
authors.forename: Lucia
authors.initials: L
authors.lastname: Kim
authors.forename: Suk-Jin
authors.initials: SJ
authors.lastname: Choi
authors.forename: In-Suh
authors.initials: IS
authors.lastname: Park
authors.forename: Joon-Mee
authors.initials: JM
authors.lastname: Kim
authors.forename: Young-Chae
authors.initials: YC
authors.lastname: Chu
keywords: Cytology; Micropapillary; Urine; Urothelial carcinoma