Small endoscopic biopsies of the ureter and renal pelvis: pathologic pitfalls.

Technical advances in endoscopic equipment have led to increased ureteroscopic biopsies of the upper urinary tract, resulting in limited biopsy material. We retrospectively reviewed 76 consecutive mid-upper ureter and renal pelvis biopsies submitted for consultation from January 2004 to January 2009, where follow-up was obtainable. There were 49 (64.5%) males and 27 (35.5%) females. Thirty-nine (51.3%) of the biopsies were from the ureter with the remaining 37 (48.7%) from the renal pelvis. The mean age was 70 years for males and 71 for females (range: 24 to 89). At consultation, the most common diagnoses were benign urothelium (n=25, 32.9%); atypical (n=17, 22.4%); low-grade noninvasive papillary urothelial carcinoma (n=10, 13.2%); and high-grade noninvasive papillary urothelial carcinoma (n=8, 10.5%). In cases where a definitive diagnosis could not be reached on expert review, it was mainly because of the limited size of the biopsy, absence of papillary fronds, crush artifact, and distorted architecture. There were 7 major discrepancies between the outside and second opinion diagnosis, where all of the cases were initially diagnosed as an urothelial neoplasm, yet was non-neoplastic upon review. Strips of urothelium without well-developed fibrovascular cores, polypoid ureteritis/pyelitis, and reactive urothelium mimicked urothelial neoplasms. In 5 of these 7 cases, there was no gross lesion suspicious of a tumor present according to the urologist. Overall, 33 of the 44 (75%) cases with a mass noted by the urologist or by radiography was found to have a neoplasm at follow-up. Conversely, 24 of the 32 (75%) cases without a grossly suspected tumor had no neoplasm at follow-up. The association between the histologic presence of a neoplasm at follow-up and the presence of a clinically suspected tumor was highly significant (P<0.0001). Pathologists need to recognize that in almost 1 of the 4 renal pelvic/ureteral biopsies a definitive diagnosis cannot be made because of the inadequate tissue. Caution must be exercised in the evaluation of these limited specimens, especially in the absence of a clinically suspected tumor.