Secondary neoplasms of the bladder are histological mimics of nontransitional cell primary tumours: clinicopathological and histological features of 282 cases

AIMS: The incidence, anatomical localization and histological appearances of secondary neoplasms of the urinary bladder are described, with emphasis on the points of distinction from primary tumours. METHODS AND RESULTS: A retrospective study of cases at the Royal Hospitals Trust yielded a total of 282 secondary bladder neoplasms, representing 2.3% of all malignant bladder tumours in surgical specimens. The commonest primary sites were the colon (21% of secondary neoplasms), prostate (19%), rectum (12%) and cervix (11%). Most tumours from these sites reached the bladder by direct spread. The most common sites of origin of tumours metastatic to the bladder were stomach (4.3% of all secondary bladder neoplasms), skin (3.9%), lung (2.8%), and breast (2.5%). Secondary tumour deposits were almost always solitary (96.7%), and 54% were located in the bladder neck or trigone. Histologically, 54% of secondary tumours were adenocarcinomas. Immunohistochemical staining patterns with prostate-specific acid phosphatase, prostate-specific antigen, carcinoembryonic antigen, chromogranin and neurone-specific enolase were similar in primary vesical and urachal adenocarcinomas and secondary adenocarcinomas from the gastrointestinal tract. CONCLUSIONS: The incidence of secondary bladder tumours is comparable to that of nontransitional cell primary tumours. Few secondary tumours have distinctive histological features, hence knowledge of the history and clinical investigations are particularly important in their diagnosis.