NBI-assisted digital flexible ureteroscopy in transitional renal cell carcinoma - an evidence-based assessment "through the looking glass" of the pathological analysis.

Introduction: Digital flexible ureteroscopy (FURS) increasingly became a routine diagnostic procedure in upper urinary tract transitional cell carcinoma (UUT-TCC). Identifying elements that may suggest the malignant nature of a lesion and obtaining biopsy specimens sufficient for a reliable pathological analysis remain difficult challenges. Narrow-band imaging (NBI) technology appears to provide a more accurate observation of the upper tract urothelium.