PMC4806760_01
A renal EWS/PNET in a 19-year-old male with right flank pain.. Notes: (A) An unenhanced CT image shows a huge mass in the right kidney with heterogeneous attenuation. (B) A venous phase CT image shows heterogeneous subtle enhancement of the mass and a dilated left renal vein with thrombosis. (C) An excretory phase CT image shows multiple septum-like structures in the mass. (D) A sagittal-reformatted image shows the lobulated contour of the mass and extension of the thrombosis in the IVC. Ultrasound (E) and Doppler (F) images show an ill-defined heterogenous hypoechoic mass with moderate vascularity in the right kidney with extension of the tumor into the IVC.. Abbreviations: CT, computed tomography; EWS/PNET, Ewing's sarcoma/primary neuroectodermal tumor; IVC, inferior vena cava.
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A 19-year-old male (Figure 1) presented at our hospital with abdominal mass. The unenhanced CT scan showed a unilateral large solid renal infiltrative mass completely replacing the right kidney (Figure 1A). The tumor showed weak or moderate heterogeneous enhancement (Figure 1B). The contrast-enhanced CT showed that the tumor contained multiple irregular septa-like structures (Figure 1C). The tumor had an extension of thrombosis into the inferior vena cava and right atrium, presenting with lower extremity edema (Figure 1D). US showed an ill-defined, irregular, and slightly echogenic mass without acoustic shadowing, which replaced the right kidney completely (Figure 1E and F). Color Doppler flow imaging (CDFI) showed a moderate blood flow within the mass (Figure 1F).
PMC4806760_02
A 43-year-old male with abdominal mass.. Notes: (A) An unenhanced CT image shows a large mass in the left kidney with hemorrhage. (B) A contrast-enhanced CT image shows a thrombus in the left renal vein. (C) A sagittal-reformatted image shows the enlargement of the aortocaval lymph node compressing the artery. (D) A lung window setting shows the presence of metastatic lung nodules. (E) A photograph of a gross specimen shows a white and gray mass with hemorrhage and necrosis. (F) A Doppler image shows an ill-defined heterogenous hyperechoic mass with a little vascularity in the left kidney.. Abbreviation: CT, computed tomography.
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A 43-year-old male (Figure 2) presented at our hospital with abdominal pain and abdominal mass. The unenhanced CT scan showed a unilateral large solid renal infiltrative mass completely replacing the left kidney (Figure 2A). The patients had renal vein thrombosis and a metastasis to the regional lymph nodes (Figure 2B and C). A lung metastasis was detected in the patient at the initial diagnosis (Figure 2D). CDFI showed moderate blood flow within the mass (Figure 2F).
Hematoxylin and eosin stain demonstrates a malignant, monotonous population of small round blue cells (original magnification: x200).
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The histopathology reports also revealed a small round blue cell tumor (Figure 3).
Strong membranous expression of CD99 (original magnification: x200).
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On immunohistochemistry, the tumor cells stained positive for CD99 (Figure 4), CD117, Syn and EWS rearrangement (EWS-FLI1 translocation) on fluorescent in situ hybridization.