Sarcomatoid Renal Cell Carcinoma
The sarcomatoid areas are composed of high-grade pleomorphic cells with abundant eosinophilic cytoplasm, large vesicular nuclei and prominent nucleoli. Acute inflammatory cells are scattered in the background stroma. The most commonly seen pattern in sarcomatoid renal cell carcinoma is undifferentiated spindle cell sarcoma. Other patterns that may be encountered include leiomyosarcoma, rhabdomyosarcoma, chondrosarcoma, osteosarcoma, angiosarcoma.