A previously healthy woman, aged 38 years, presented with a 3-month history of fatigue, dyspnea on exertion, significant weight loss, and severe left flank pain; her symptoms restricted any work activities. Laboratory test results were notable for hypercalcemia (corrected serum calcium, 12.8 mg/dL), anemia (9.3 g/dL), and lactate dehydrogenase elevation (>1.5 times the upper limit of normal). A CT scan revealed a 14-cm left renal mass and multiple lung and mediastinal lymph node metastases. A surgical open biopsy was performed; histopathological analysis concluded clear cell renal carcinoma (RCC) with 30% sarcomatoid features. The patient was diagnosed with International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) poor-risk metastatic RCC with sarcomatoid features. She started first-line systemic treatment.