case_images: PMC10894445_01
case_images: Coronal CT image of primary Ewing sarcoma of the left kidney measuring 25 cm x 18 cm x 18 cm (arrow). CT: computed tomography
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case_images: PMC10894445_01_cureus-0016-00000052970-i01.jpg
case_images: FIG1
case_images: A CT scan was performed, which showed a large heterogenous non-calcific left renal exophytic mass measuring approximately 25 x 18 x 18 cm (Figures 1, 2).
case_images: Axial CT image of primary Ewing sarcoma of the left kidney measuring 25 cm x 18 cm x 18 cm (arrows). CT: computed tomography
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case_images: PMC10894445_01_cureus-0016-00000052970-i02.jpg
case_images: FIG2
case_images: A CT scan was performed, which showed a large heterogenous non-calcific left renal exophytic mass measuring approximately 25 x 18 x 18 cm (Figures 1, 2).
case_images: H&E (20x) sections showing sheet-like growth pattern, uniform small round cells, finely stippled chromatin, inconspicuous nucleoli, and scant clear to eosinophilic cytoplasm with indistinct cytoplasmic membranes. H&E: Hematoxylin and eosin
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case_images: PMC10894445_01_cureus-0016-00000052970-i03.jpg
case_images: FIG3
case_images: A subsequent biopsy of the left renal mass was performed which showed cores of a malignant neoplasm, composed of sheets of round blue cells, with a high nucleocytoplasmic ratio, round nuclei, and focal areas of necrosis (Figure 3).
case_images: FLI-1 immunohistochemical stain (10x) demonstrates strong nuclear positivity representing a surrogate marker for characteristic EWSR-FLI-1 translocation. FLI-1: Friend leukemia integration 1; EWSR: Ewing sarcoma breakpoint gene
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case_images: PMC10894445_01_cureus-0016-00000052970-i04.jpg
case_images: FIG4
case_images: IHC staining showed positivity of CD99 and FLI-1, a focal weak positivity of synaptophysin, and an intact INI-1 (Figures 4, 5).
case_images: CD99 immunohistochemical stain (4x) shows strong diffuse membranous positivity in the tumor cells
case_images: cureus-0016-00000052970-i05.jpg
case_images: PMC10894445_01_cureus-0016-00000052970-i05.jpg
case_images: FIG5
case_images: IHC staining showed positivity of CD99 and FLI-1, a focal weak positivity of synaptophysin, and an intact INI-1 (Figures 4, 5).