Abstract

Renal cell carcinoma (RCC) with sarcomatoid differentiation accounts for 4% of all RCC cases. This aggressive variant is characterized by spindle-shaped tumor cells and carries a high risk of metastasis and poor outcomes. Accurate diagnosis is crucial due to its aggressiveness and the limited treatment options. A 55-year-old male presented to the nephrology department with right lumbar pain, hematuria, and burning micturition. Radiology showed an enlarged right kidney with a hetero-echoic mass (7x5x2cm) across the mid and lower pole. He underwent right nephrectomy followed by histopathological examination and immunohistochemistry. Gross examination showed a well-circumscribed lower pole lesion along with hemorrhagic areas in the upper pole. Microscopy revealed spindle-shaped tumor cells in an inflammatory background, consistent with the diagnosis of RCC with sarcomatoid differentiation. Immunohistochemistry was positive for both epithelial and mesenchymal markers. Thus, diagnosed as renal cell carcinoma with sarcomatoid differentiation. ‘’Sarcomatoid renal cell carcinoma” is not a distinct subtype of RCC as it occurs with all histologic subtypes of RCC. It originates from epithelial-mesenchymal transition. Even a small component of sarcomatoid differentiation independently predicts poor survival compared to primary RCC. Therefore, accurate documentation of sarcomatoid differentiation in pathology reports is vital for precise prognostic assessment and guiding treatment strategies. More research is needed on sarcomatoid renal cell carcinomas (SRCCs) due to ineffective treatments. Immune checkpoint blockade therapies show promise, but large-scale efforts are crucial for better solutions.

Key words: Epithelial-mesenchymal transition, Heteroechoic mass, renal cell carcinoma, Sarcomatoid differentiation, Spindle-shaped cells