Sarcomas and sarcomatoid and mixed malignant tumors of the kidney in adults—part III

Abstract

The clinical and pathologic features of 43 cases of malignant renal tumor with mixed histopathologic features are presented. The characteristic features of embryonal nephroblastoma (Wilms' tumor) of infancy and childhood were seen in five adult cases. Renal-cell carcinoma, intimately associated with a more pleomorphic spindle-cell or giant-cell malignancy resembling sarcoma, was the lesion in 37 cases. Areas of osteogenic sarcoma were noted in three tumors of this latter group and foci of transition of carcinoma cells to pleomorphic sarcomatoid cells could be demonstrated. A third distinctive mixed malignant tumor (one case in the series) was a transitional-cell carcinoma of the kidney with a pleomorphic malignant-appearing spindle-cell stromal component. The term “sarcomatoid” is appropriate in the present incomplete state of knowledge of these unusual malignant neoplasms.