Diagnostic dilemmas for upper-tract urothelial carcinoma (UTUC)-grade discordance between endoscopic biopsy and final surgical pathology.

Significant predictors for under grading included familial history of Lynch Syndrome or Lynch-associated cancers (OR = 3.22, P = 0.003) and clinical tumor size greater than 2 cm (OR = 1.59, P = 0.031).

Nearly 50% of low-grade biopsy tumors were upgraded at final nephroureterectomy pathology.

Additional investigation integrating adjuvant diagnostic modalities, cytology at time of diagnosis, and enhanced imaging for larger tumors may aid in appropriate risk stratification.