Sarcomatoid Carcinoma of Renal Pelvis with Abundant Heterologous Osteosarcomatous Element: A Case Report.

A 47-year-old male presented with haematuria and flank pain for two weeks. Ultrasonography and renal scan revealed a poorly functioning left kidney with multiple calculi. Simple nephrectomy was performed and the specimen revealed a mass in his renal pelvis which showed both carcinomatous and sarcomatous components on microscopy. The sarcomatous component consisted of diffuse pleomorphic osteoblasts with intervening lacy osteoid, giving an osteosarcoma-like appearance. These areas of tumour were strongly positive for vimentin and osteopontin. The carcinomatous component was transitional cell carcinoma. Patchy areas of squamous cell carcinoma which were positive for pancytokeratin on immunostaining were also seen. Few weeks later, the patient presented with metastatic lesions in the sacrum. After nephrectomy, the patient underwent palliative radiotherapy of the spine followed by sunitinib therapy. A month later, there was recurrence at the site of surgery. The patient succumbed to his illness within five months of diagnosis. This report describes an extremely rare case of carcinoma, renal pelvis with predominantly osteosarcomatous areas.