Primary Renal Ewings Sarcoma/Primitive Neuroectodermal Tumor (PNET) Of The Kidney, Can It Be Diagnosed On Imaging? A Case Report

Case Presentation

Austin J Radiol. 2014;1(1): 4.

Primary Renal Ewings Sarcoma/Primitive Neuroectodermal Tumor (PNET) Of The Kidney, Can It Be Diagnosed On Imaging? A Case Report

Katkar AS1*, Vinu-Nair S1, Savage J2 and Chintapalli K1

1Department of Radiology, University of Texas Health Science Center at San Antonio, USA

2Department of Pathology, University of Iowa Hospitals and Clinics, USA

*Corresponding author: Katkar AS, Department of Radiology, University of Texas Health Science Center at San Antonio, USA

Received: May 22, 2014; Accepted: June 02, 2014; Published: June 06, 2014

Abstract

Primary renal Ewing Sarcoma⁄primitive Neuroectodermal Tumor (PNET) of the kidney represents a rare aggressive pathologic entity seen in children and young adults. Here we present a case of a 46 year old woman who presented with bilateral lower quadrant abdominal pain and microscopic hematuria. Radiologic imaging demonstrated a large heterogeneous, vascular mass involving the upper pole of right kidney causing diffuse enlargement of kidney on ultrasound. Further imaging with a CT scan showed a moderately enhancing, diffusely infiltrating right upper pole mass with a tumor thrombus in right renal vein that extended into the infrahepatic portion of the inferior vena cava. An ultrasound guided biopsy of the lesion demonstrated a mass composed of neoplastic cells with primitive histomorphologic features and expression of vimentin, CD99 (MIC2), FLI–1, and BCL–2. The tumor was negative for WT–1, pankeratin, synaptophysin, chromogranin and CD45. FISH analysis showed a rearrangement of EWSR1 in 89% of cells. The patient subsequently underwent a right nephrectomy, IVC thrombectomy and regional lymph node dissection. The imaging features of renal PNET can be uncharacteristic and this tumor is mainly diagnosed based on the combination of pathological and radiological findings. By presenting this case report we expect to further knowledge on the imaging features and various options for preoperative diagnosis of renal ES⁄ PNET. Based on the case that we are presenting, we suggest diffuse infiltrative appearance of the tumor, moderate grade enhancement, peripheral areas of hemorrhage and necrosis and tumor thrombus in renal vein and IVC can suggest the imaging diagnosis of renal ES⁄PNET preoperatively.

Keywords: Renal Primitive Neuroectodermal Tumor (Rpnet); Renal Ewing Sarcoma (EWS); Computerized tomography; Sonography; Ultrasound

Introduction

Primary Ewing Sarcoma⁄Primitive Neuroectodermal Tumor of the kidney (ES⁄PNET) represents a rare group of small round cell tumor that is characterized by an aggressive clinical course. Historically, Ewing sarcoma and primitive neuroectodermaltumors were considered to be separate pathologic entities; however, molecular studies have established that these tumors are a part of the same tumor family and exhibit similar biologic behavior. As such, the term Ewing sarcoma now encompasses both entities [1]. ES⁄PNET tumors are most commonly identified in the axial skeleton, appendicular skeleton and central nervous system; however xtracranial and extraosseous tumors have also been described [2]. ES⁄PNET lesions of the kidney are exceedingly rare and were first reported by Seemayer and colleagues in 1975 [3]. Subsequent cases in the literature have shown that this tumor tends to affect young adults (median age 28) with a slight male predominance. Patients usually remain asymptomatic until tumor reaches large size and usual presenting symptoms are flank and⁄or abdominal pain (85%), a palpable mass (60%) and hematuria (37%) [4]. Systemic symptoms such as weight loss (14.5%) and fever (9.7%) may occur and must be differentiated from infectious etiologies [5]. The prognosis of renal ES⁄PNET is generally poor, with a 5 year disease–free survival rate of 45–55% and an overall survival of 20% [5].

Here we present a case of primary renal ES⁄PNET in a 46 year old female and discuss the radiographic and morphologic features of this lesion.

Case Presentation

A 46 year old woman with a history of hypertension, hyperlipidemia and nephrolithiasis presented to the emergency room with a 2–3 week history of intermittent bilateral lower quadrant abdominal pain and nausea. Initial laboratory studies showed trace hematuria and 2+ proteinuria. An abdominal ultrasound was performed and showed a heterogenous vascular mass in the upper pole of right kidney with tumor thrombus extending into the right renal vein and Inferior Vena Cava (IVC) (Figure 1A,1B &1C). A staging contrast enhanced CT scan of the abdomen revealed a 15.7 cm lobulated, infiltrative mass in the upper pole of right kidney causing diffuse enlargement of the kidney with diffuse, moderate heterogenous enhancement following intravenous contrast administration. As seen on the ultrasound, the tumor showed extension into the right renal vein and IVC, ending just below the level of the hepatic veins (Figure 2A,2B,2C & 2D). Despite the large size of the mass, the contour of the kidney was well maintained. The mass showed a few hypoenhancing areas, likely representing hemorrhage and necrosis. There was no evidence of metastatic disease at the time of initial presentation. Based on these imaging features, a diagnosis of renal cell carcinoma with tumor thrombus extending into renal vein and IVC was rendered.