Pathology of urinary tract tumours

The urinary tract encompasses the kidneys, ureters, urinary bladder and urethra. Most of the urinary system is lined by specialized transitional epithelium called urothelium. Tumours that arise from this epithelium share similar histopathological features, no matter whether they arise in the renal pelvis, ureters or the urinary bladder. The spectrum of disease covered includes benign lesions arising from the urothelium, flat urothelial lesions, papillary urothelial cell neoplasms through to invasive urothelial cell carcinomas. Other tumours which are occasionally seen within the urinary tract and variants of invasive urothelial cell carcinoma are also briefly discussed. A description of the most recent staging and grading is given along with highlighting the need for appropriate clinico-pathological correlation. Tumours arising from the renal parenchyma are also detailed; including benign entities such as oncocytoma and angiomyolipoma as well as malignant tumours under the heading of renal cell carcinomas. We also outline some recent molecular advances in the understanding of renal neoplasia and the treatment options these advances have brought for metastatic renal cell carcinoma.