Contrast-enhanced ultrasound features of primary renal Ewing-like undifferentiated small round cell neoplasm: a case report.

This article reports on the diagnosis and treatment of a patient with a renal Ewing-like undifferentiated small round cell neoplasm. The patient, a 56-year-old man, presented to our hospital on March 14, 2025, complaining of "blood clots in the urine for 2 days" and "a mass in the right kidney detected on physical examination 2 days prior." On March 21, 2025, he underwent a "right renal mass needle biopsy" under local infiltration anesthesia. Postoperative pathology: (right renal mass) malignant tumor with necrosis; immunohistochemical findings consistent with renal Ewing-like undifferentiated small round cell neoplasm. Postoperative follow-up: The patient's condition progressed after six cycles of chemotherapy. Immunotherapy combined with anti-angiogenic targeted therapy was planned but proved ineffective; the patient ultimately died of multiple organ failure.