What is the pathophysiology of rare forms of bladder cancer?

Updated: Feb 23, 2021
  • Author: Kara N Babaian, MD, FACS; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Answer

Adenocarcinomas account for less than 2% of primary bladder tumors. These lesions are observed most commonly in exstrophic bladders and are often associated with malignant degeneration of a persistent urachal remnant.

Other rare forms of bladder cancer include leiomyosarcoma, rhabdosarcoma, carcinosarcoma, lymphoma, and small cell carcinoma. Leiomyosarcoma is the most common sarcoma of the bladder. Rhabdomyosarcomas most commonly occur in children. Carcinosarcomas are highly malignant tumors that contain a combination of mesenchymal and epithelial elements. Primary bladder lymphomas arise in the submucosa of the bladder. Except for lymphomas, all these rare bladder cancers carry a poor prognosis.

Small cell carcinoma of the urinary bladder is a poorly differentiated, malignant neoplasm that originates from urothelial stem cells and has variable expression of neuroendocrine markers. Morphologically, it shares features of small cell carcinoma of other organs, including the lung.


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