Metaplastic conditions of the bladder.

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD? Urologists are often confronted with cystoscopic appearances that at times are abnormal but non-specific, may mimic urothelial carcinoma or in some instances are quite bizarre given the clinical scenarios in which they occur (e.g. changes associated with a catheter will be more obvious than a de-novo presentation of cystitis cystica). Metaplasias of the bladder urothelium make up the majority of such cases. Furthermore, when confronted with a pathological diagnosis of a metaplasia within the bladder- what are the implications for the patient and how should they be followed-up? This review provides a concise summary of the pathological features of the various metaplasias that occur in the bladder and briefly describes their current treatment and requirement for follow-up. Metaplasia of the bladder urothelium occurs commonly in response to local injury. Usually the changes are reversible, but some conditions may be premalignant. This review describes the different metaplastic entities and their clinical significance. Most importantly, keratinising squamous metaplasia is a precursor to the development of bladder cancer, and requires treatment and long term follow up. The role of intestinal metaplasia in the development of cancer is uncertain, and these patients require follow-up until further evidence is obtained on the outcome of this entity.