Primary osteosarcoma of bladder treated with cystectomy

Bladder osteosarcoma is extremely rare tumor. There are about 30 cases described in the literature. Poor prognosis with lethal outcome within one year could be expected, although successful treatments were reported. We present a case of primary bladder osteosarcoma successfully treated with cystectomy, free of the disease for two years. A 63 years old man was admitted with history of blood in urine during the last month. CT showed 5 cm bladder mass and suspected infiltration of rectum. Transurethral resection was performed and after histology revealed osteosarcomma a cystectomy was done. Histology found a mesenhimal malignant tumor made from spindle like cells, areas of osteoid surrounded with malignant osteoblast type cells showing trabeculae resembling structures, cartilage with atypical forms of hondrocytes and osteoclasts. Areas of urothelium were of normal structure and without atypical or malignant cells. Immunochemistry staining was positive for vimentin, S-100, CD31, CD99, CD68 and Ki67, but negative for cytokeratin, epithelial membrane antigen (EMA) and desmin. Bone forming bladder tumors can be divided into the three groups: carcinosarcoma, transitiocellular carcinoma with osseous metaplasia and osteosarcoma. Historically four origin theories were proposed: mesenchymal remains of Wolfian body, blood transfer of cells, metaplasia and theory of alkaline-phosphatase rich mucosa triggering osteogenic differentiation into neoplastic mesenchymal cells has been held for true. Our case showed that with good coordination of pathologist and urologist combined with prompt and aggressive therapy even a locally advanced disease can be treated.