Primary Ewing Sarcoma Within an Autosomal Dominant Polycystic Kidney: A Case Report.

Ewing sarcoma, that originates from neuroectoderm, is typically encountered in the bone and soft tissue of children and young adults and rarely presents as a primary renal tumor. Autosomal dominant polycystic kidney disease, which is the most common type of inherited kidney disease, has been debated to be associated with an increased risk of kidney cancer. This report describes the first documented case of primary Ewing sarcoma arising within an autosomal dominant polycystic kidney. A 44-year-old male with end-stage kidney disease secondary to autosomal dominant polycystic kidney disease presented with left flank pain. Imaging revealed a 14 cm heterogeneous mass in the lower pole of the polycystic left kidney. The patient underwent laparoscopic left nephrectomy, and pathology examination confirmed the diagnosis of primary Ewing sarcoma. He received 12 cycles of adjuvant chemotherapy, including vincristine, dactinomycin, and cyclophosphamide. Despite treatment, disease relapse occurred 13 months after the initial diagnosis, and the patient died 3 months later. Primary Ewing sarcoma of the kidney is a rare malignancy with nonspecific clinical and imaging features. It is associated with a poor prognosis due to delayed diagnosis, high metastatic potential, and frequent recurrence.