Other Malignancies Primary and Metastatic and Miscellaneous Lesions

Abstract

Bladder cancer is histologically classified as urothelial carcinoma (UC) and non-urothelial carcinoma (non-UC). UC is the most prevalent histologic type, worldwide, and constitutes 90 % of bladder cancers. It may be pure UC or associated with divergent histological differentiation including squamous cell carcinoma (SqCC), adenocarcinoma, and other aberrant morphology. Primary non-urothelial bladder tumors are rare, representing less than 5 % of all bladder tumors combined, in Europe and North America. Non-urothelial tumors include pure SqCC, adenocarcinoma, small cell carcinoma, and other uncommon tumors. Primary non-UC may be histologically and cytologically difficult to distinguish from UC with divergent differentiation in small biopsy or cytological samples, which ranges from 7 to 81 %. Primary non-UC of the bladder has an aggressive biological behavior, often present at an advanced stage of disease, and despite aggressive surgical management these tumors have a poor overall survival.