PMC5116656_01
CT scan with axial (A) and coronal (B) views showing heterogeneously enhancing mass within the right kidney.
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A three-phase kidney CT scan revealed a 4.6 cm x 2.6 cm x 2.8 cm heterogeneously enhancing renal parapelvic mass without extension into the collecting system or renal vein (Fig. 1A). The tumor was located centrally near the hilum and traversed into the lower pole of the kidney (Fig. 1B).
Gross examination demonstrates a well-circumscribed yellow tan nodular mass arising in the lower pole, near the hilum, of the right kidney.
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Gross examination demonstrates a well circumscribed, nodular yellow lesion at the renal hilum, measuring up to 4.3 cm (Fig. 2).
(A) Histologic examination shows a hypercellular spindled lesion with prominent peripheral lymphoid aggregates and scattered hyalinzed vessels (original magnification 40 x ). (B) An S100 immunohistochemical stain is strongly positive in the spindled cells (red chromogen, original magnification 100 x ).
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There are numerous hyalinized vessels throughout, with scattered lymphoid aggregates lining the periphery (Fig. 3A). A panel of immunohistochemical stains was performed, which reveals that the tumor cells are strongly positive for S100 (Fig. 3B) and negative for smooth muscle actin, desmin, HMB-45, Mart-1, MiTF, and CD34.