Pathology > Study Images > Urinary Tract > Tumors of the Kidney > Introduction
Objectives Anat & Hist Introduction Benign Tumors Malignant Tumors

II. Introduction

Tumors of the kidney may be classified according site as those arising in the renal parenchyma and those originating in the renal pelvis. Tumors arising in the parenchyma can be classified according to the cell of origin (histogenetic) into those arising from epithelium (renal tubules and urothelium), messenchymal tissue (renal interstitium) and embryonic tissue and according to biologic behavior as benign or malignant.

Transitional epithelium lines the urinary tract starting from the renal pelvis and extending through the ureter, the urinary bladder, and the proximal two-thirds of the urethra. About 95% of tumors of the renal pelvis and the ureter are epithelial in origin and 80% of these are malignant with transitional cell carcinoma accounting for about 90%. Carcinomas occurring at both sites show the same morphologic spectrum and clinical associations as those seen in the urinary bladder. However, their combined frequencies are only about a tenth of that of bladder carcinomas. The major prognostic features of cancers of the pelvis and ureter are the same as those for bladder carcinoma and site does not appear important. In view of these, tumors of the renal pelvis as well as those of the ureter will be discussed with tumors of the bladder.

Objectives Anat & Hist Introduction Benign Tumors Malignant Tumors