Ewing's sarcoma/primitive neuroectodermal tumor of the kidney: a case report and literature review

Abstract

Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET) is a malignant bone, and soft-tissue tumor derived from neuroectoderm. It occurs in pediatric adolescents with the histopathological features of invasiveness. Renal involvement is extremely rare, which is limited to case reports and small case series. Most patients showed non-specific symptoms, such as abdominal pain and severe hematuria. The corresponding diagnosis was based on pathological features and immunohistochemical detection. So far, the characteristics of computed tomography (CT) have been rarely described in these cases. We report an 18-year-old man diagnosed with renal ES/PNET, who suffered from a sudden left flank pain associated with gross hematuria. The CT images showed an irregular soft tissue mass with a size of 7.3 cm × 7.0 cm × 9.0 cm. The patient underwent laparoscopic nephrectomy of the left kidney. The final diagnosis of renal ES/PNET was confirmed by immunohistochemical detection and fluorescence in situ hybridization of the nephrectomy specimen. We want to point out that CT scanning is still a useful method for preliminary assessment in preoperative diagnosis.

Keywords: Ewing sarcoma (ES); computed tomography (CT); kidney; nephrectomy; primitive neuroectodermal tumor (PNET).

Figure 1

CT and gross specimen images of tumor. (A) Unenhanced axial CT image shows a large multilobulated mass in the interpolar region of the left kidney; (B) corticomedullary axial CT image shows the tumor with areas of necrosis, varying degrees of irregular enhancement; (C) nephrogenic axial CT image shows a sign of tumor thrombus extends into main left kidney vein invasion; (D) gross specimen of diseased tissue. CT, computed tomography.

Figure 2

Histologic and immunohistochemical images of tumor. (A) Microscopically, histologic analysis of hematoxylin and eosin staining (×100) revealed that the tumors were composed of a monotonous population of small round cells. Extensive necrosis was also observed in histologic sections; (B,C,D) immunohistochemical staining showed positive expression for CD99 (×200), FLI-1 (×400), and SYN (×400).