Tumours of the Urinary System

Chapter 1 - Anatomy of the GU Tract and Histology of GU Tumours

Tumours of the Urinary System Figure 1

Courtesy http://www.uofmchildrenshospital.org/healthlibrary/Article/40091

Urothelium is present in the kidney pelvis, ureters, urinary bladder, and the urethra.

Urothelial neoplasms can occur in all of these organs but >90% are in the urinary bladder.

The normal bladder wall consists of several tissue layers, the distinction of which is critical for bladder cancer staging.

Tumours of the Urinary System Figure 2

Courtesy http://www.cancerresearchuk.org/

The urothelium covers the inner surface of the bladder. The connective tissue layer between the urothelium and the muscular bladder wall is the lamina propria.

The staging system of urothelial neoplasms is unusual as two non-invasive lesions exist: non-invasive papillary carcinoma (pTa) and carcinoma in situ (pTis).

The invasive stages are pT1: invasion of lamina propria; pT2: invasion of muscular wall; pT3: invasion of perivesical fat; pT4: invasion of adjacent organs.

Staging of bladder neoplasms is critical for treatment decisions, but challenging for pathologists.

This is due to the nature of transurethral tumour resection, because it always leads to fragmentation and substantial crush artefacts in the removed tissues.

The distinction between pTa and pT1 tumour can be very challenging and is subject to high interobserver variability.

Revision Questions

  1. What is the most common site for urothelial cancer?
  2. What is the difference between stage pTa and pTis?
  3. Which tumour stages are subject to particularly high interobserver variability?
Last update: 08 September 2015