Neoplasms of the upper urinary tract: a review with focus on urothelial carcinoma of the pelvicalyceal system and aspects related to its diagnosis and reporting

Abstract

Tumors of the renal pelvis account for approximately 7% to 8% of all renal malignancies, greater than 90% of these are of urothelial (transitional cell) origin. These tumors more typically occur in the sixth to eight decade with a slight male preponderance. Varying risk factors for urothelial carcinomas of the upper tract are recognized including environmental and occupational hazards, chemotherapeutic exposure, and previous history of urinary bladder or ureteral carcinomas. Tumor multifocality is frequent and additional tumors may arise in the ureter, bladder, or on the contralateral side. The histopathologic nuances presented by urothelial carcinoma in this region are generally similar to those in the urinary bladder. Though the World Health Organization 2004/International Society of Urological Pathology system used in the bladder is customarily also employed for grading of urothelial tumors of this region, its prognostic significance at this site is not entirely clear as most tumors are treated with nephroureterectomy irrespective of the grade of the tumor. Histologic grade may be an independent prognostic factor in papillary pT1 tumors; however, most pT2 and higher stage tumors tend to be nonpapillary and of higher grade. Despite advances in treatment modalities with sophisticated endoscopic techniques, tumor stage remains the most important prognostic factor. There are several confounding issues related to staging such as the variable presence and thickness of subepithelial connective tissue and muscularis in the renal calyces, renal pelvis, and the ureter; intratubular pagetoid cancer spread (pTis vs. pT3); and assessing invasion in papillary neoplasms with endophytic or inverted growth. Careful gross examination with adequate sampling and understanding the microanatomy of the pelvicalyceal wall are crucial for accurate stage assignment. Poor fixation of large friable tumors and processing artifacts may compound difficulties in accurate staging. This review focuses on urothelial carcinoma of the upper tract highlighting issues related to its diagnosis, staging, and reporting.