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).