Challenges in the Diagnosis and Management of Renal Cell Carcinoma With Sarcomatoid Differentiation: A Case Report.

Metastatic sarcomatoid renal cell carcinoma (sRCC) is a significant therapeutic and diagnostic challenge due to its rarity and aggressiveness, which contribute to its poor prognosis. This case report presents the case of a 47-year-old Caucasian man with shortness of breath and right-sided abdominal pain. History revealed an extensive smoking history, a left renal mass diagnosed two months ago with inconclusive results, and an enlarged mass on computed tomography (CT) scan one week ago in an emergency department (ED) visit that showed signs consistent with metastatic disease. CT scan on presentation revealed a right posterolateral chest wall mass measuring 8.5×3.5 cm between the 10th and 11th ribs, as well as multiple bilateral pulmonary metastases. CT scan of the head revealed a soft tissue mass anterior to the epiglottis within the vallecula. Left renal pole mass was also consistent with neoplasm, with stable surrounding mass-like densities consistent with adenopathy and involvement of the adrenal gland. Histopathological examination of the 11 cm right chest wall mass biopsy revealed sRCC due to the visualization of spindle to epithelioid tumor with focal clear cell morphology and a prominent vascular network leading to a nested appearance. Management of his symptoms included thoracocentesis of the pleural effusion, nasal cannula due to low partial pressure of oxygen (PO2), pleurodesis, and trending down of the hypercalcemia. Oncology confirmed the spindle cell neoplasm due to stage IV renal cancer; the patient was transferred to hematology-oncology for further evaluation, but soon after succumbed to the complexities of metastatic disease. This case highlights the challenges of the management and diagnosis of metastatic sRCC over a three-week inpatient service, ultimately revealing a poor prognosis due to the aggressiveness and time of diagnosis, emphasizing the need for early detection methods and personalized treatment strategies. Further research is needed to explore novel therapeutic approaches to tackle this rare and aggressive variant of RCC.