Editing Bladder Cancer: Pathology (section)

=== Grading ===
* '''<span style="color:#ff0000">Classified as low grade (LG) vs. high grade (HG)</span>'''
** 1973 World Health Organization defined 3 categories: grades 1, 2, and 3
*** Middle category was overreported
** 2004, International Society of Urologic Pathologists updated classification to 3 categories:
*** Papillary urothelial neoplasm of low malignant potential (PUNLMP)
*** Low-grade
*** High-grade
** 2016 reviewed system without major changes
** With the 2004/2016 WHO/ISUP system, 30-40% of the former grade 2 lesions with bland cytological features were re-classified as LG, while the other 60-70% were re-classified as HG
** '''TaLG lesions recur at a rate of 50-70% and progress in ≈5% of patients'''
** '''T1HG lesions recur at a rate > 80% and progress in 50% of patients''' [different numbers than Chapter 93]
** The variance in biologic behavior for LG versus HG lesions correlates with the known dual molecular lines of genetic development for these two pathways and supports the concept that HG and LG cancers may be considered as essentially different diseases; LG papillary tumors tend to exhibit relatively few chromosomal abnormalities compared to HG tumors