American Urological Association - Papillary Urothelial Neoplasm of Low Malignant Potential
Papillary Urothelial Neoplasm of Low Malignant Potential
- Non-benign category of papillary urothelial neoplasm with negligible risk of progression.
- Avoids psychosocial and financial implications of cancer diagnosis but allows patient to be followed closely.
- Relatively common in younger patients; most common bladder tumor in adolescents.
- Cystoscopy shows <2 cm papillary tumor.
- Papillae (with fibrovascular core) lined by hyperplastic-appearing urothelium (thicker than urothelial papilloma) (image A).
- (Very) Well-maintained cell polarity from base towards the surface.
- Nuclei elongated or oval (image B).
- Papillae typically slender with minimal branching.
- Minimal to absent nuclear atypia with rare mitosis usually at base.
- Recurrence rate of 17-62% and progression rate to higher grade of <8%.
- Wide recurrence rate may reflect interobserver variability interpretation with low-grade papillary urothelial carcinoma and urothelial papilloma.