Urothelial nonneoplastic lesions
Flat lesions with reactive changes

Author: Monika Roychowdhury, M.D. (see Authors page)

Revised: 16 November 2018, last major update June 2016

Copyright: (c) 2003-2016,, Inc.

PubMed Search: Flat lesions with reactive changes
Cite this page: Roychowdhury, M. Flat lesions with reactive changes. website. Accessed November 18th, 2018.
Definition / general
  • Inflammatory atypia characterized by mild nuclear abnormalities in acutely or chronically inflamed urothelium
  • Uniformly enlarged and vesicular nuclei, central prominent nucleoli
  • May have frequent mitotic figures involving the lower layers of urothelium
Clinical features
  • May have history of cystitis, infection, instrumentation, stones or therapy
  • Not neoplastic but may coexist with dysplasia or carcinoma in situ
  • Most patients present with hematuria or irritative symptoms (frequency, urgency, dysuria)
Prognostic factors
Gross description
  • Erythematous or inflamed urothelium cystoscopically
Microscopic (histologic) description
  • Urothelium is normal to slightly thickened and shows morphologic evidence of maturation
  • Cells have abundant cytoplasm, nuclei may be enlarged and may have prominent nucleoli
  • Lamina propria is usually inflamed with inflammation extending to the mucosa
  • No nuclear hyperchromasia, no pleomorphism, no coarse chromatin pattern
Positive stains
  • CK20(limited to umbrella cells), CD44(stains all cell layers)
Negative stains
Differential diagnosis