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.

PATIENTS, MATERIALS AND METHODS: During this prospective analysis, white light (WL) and NBI-assisted digital FURS were performed in 87 consecutive patients admitted for primary suspicion of UUT-TCC. The endoscopic technique comprised digital WL FURS, followed by the NBI assessment of the renal collecting system' mucosa. All suspicious areas of the pyelocaliceal urothelium were biopsied using the grasping forceps, separately for WL and NBI findings.

RESULTS

A total of 113 UUT-TCC tumors (104 pTa and nine carcinoma in situ - CIS) were confirmed by pathology in 62 patients. The patients' detection rate was significantly improved in NBI mode when compared to standard FURS (98.4% versus 91.9%, respectively), due to cases either exclusively diagnosed with UUT-TCC (8.1%) or presenting additional urothelial tumors (12.9%). Overall, 13 pTa and two CIS lesions were solely observed in NBI, which was on the other hand characterized by a significantly increased proportion of unnecessary biopsies (NBI versus WL rate of false-positive results - 17.5% versus 10.1%, respectively).

CONCLUSIONS

As additional tool for the standard WL evaluation of the pyelocaliceal system' urothelium, NBI-guided biopsies were emphasized as providing a significant diagnostic improvement during digital FURS.