Multifocal occurrence and frequent recurrence are characteristic features of @entity189 of both the urinary bladder and the upper urinary tract. To describe the clonal nature of these @entity5 , 2 theories have been proposed. The monoclonality hypothesis describes the @entity5 as descendants of a single genetically transformed cell spreading throughout the urothelium. In contrast, field cancerization caused by carcinogen exposure of the urothelium may lead to independent development of synchronous or metachronous nonrelated @entity5 at different sites of the urothelial tract. In the last 10 years, a multitude of molecular genetic studies have investigated the clonality of multifocal @entity189 . The majority of studies revealed a monoclonal origin of the @entity5 . However, most of these studies investigated advanced invasive @entity189 . A small but significant proportion of multifocal @entity189 appear to arise from different clones, supporting the field-cancerization hypothesis. @entity5 might be more common in precursor lesions and early @entity5 stages. The frequent monoclonality found in @entity1 with advanced @entity5 could be due to outgrowth of 1 @entity5 cell clone with specific genetic alterations. Two important mechanisms appear to be important for the spread of malignant cells: intraluminal seeding and intraepithelial migration. Investigation of the entire urothelial lining in @entity1 with @entity5 should provide further insight into the development of multifocal @entity189 .

Clonality of multifocal XXXX : 10 years of molecular genetic studies.

@entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'multiple tumors', 'Oligoclonal tumors', 'urothelial tumors', 'tumors'] @entity1 :: ('9606', 'Species') :: ['patients'] @entity189 :: ('MESH:D002277', 'Disease') :: ['carcinomas', 'urothelial carcinomas']
@entity189 :: (MESH:D002277,Disease) :: ['urothelial carcinomas']
