- Markedly thickened urothelium lacking cytologic atypia.
- No absolute numerical cut-off for hyperplasia, which is usually marked and easily distinguishable (image A) & (image B).
- Can be flat or papillary.
- Flat hyperplasia may be seen adjacent to low grade papillary tumors.
- Papillary urothelial hyperplasia is characterized by hyperplastic urothelium arranged in undulating mucosal folds.
- Lack of cytologic atypia and fibrovascular core (not true papillae) distinguish from papillary urothelial neoplasms, which is the main differential diagnosis.
- Suggested to be precursor lesion for low-grade papillary urothelial tumors (not the usual flat hyperplasia).