Bladder & urothelial tract
Urothelial neoplasms - noninvasive
Flat hyperplasia
Author: Monika Roychowdhury, M.D.
Last author update: 1 December 2014
Last staff update: 1 November 2021
Copyright: 2003-2024, PathologyOutlines.com, Inc.
PubMed Search: Bladder [title] Flat hyperplasia
Table of Contents
Definition / general | Epidemiology | Clinical features | Prognostic factors | Microscopic (histologic) description | Positive stains | Negative stains | Molecular / cytogenetics description | Differential diagnosisCite this page: Roychowdhury M Flat hyperplasia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bladderflathyperplasia.html. Accessed April 25th, 2024.
Definition / general
- Markedly thickened mucosa (up to 10 or more cell layers) without cytologic atypia
- May be adjacent to low grade papillary urothelial neoplasm
- By itself, has no malignant potential and requires no treatment
Epidemiology
- True incidence is not known due to lack of large scale screening studies
Clinical features
- Asymptomatic
Prognostic factors
- Isolated lesion does not have a premalignant potential
- Molecular studies suggest a preneoplastic potential in flat hyplerplasia concurrent with low-grade papillary tumors (Hum Pathol 2010;41:155)
Microscopic (histologic) description
- May occur adjacent to low-grade papillary tumors or as an isolated lesion
- Marked thickening of mucosa up to 10 or more cell layers
- Maintains morphologic evidence of maturation from basal cells to superficial cells
- Absence of cytologic atypia or mitoses
Positive stains
Negative stains
Molecular / cytogenetics description
- Genetic alterations in chromosome 9 are frequent in flat hyperplasia with concurrent low-grade papillary tumors
Differential diagnosis
