Bladder carcinosarcomas: three cases with diverse histogenesis

Carcinosarcomas of the bladder are rare. We describe three such tumours, including an apparently unique case in which the components comprised liposarcoma and poorly-differentiated transitional cell elements. A second example included chondrosarcomatous elements. These two tumours showed architectural and immunocytochemical features which suggested that they had originated as carcinomas but had subsequently differentiated along both epithelial and mesenchymal pathways. The third tumour contained both carcinoma and osteosarcoma and may represent a collision tumour.