case_images: PMC9581194_01
case_images: Imaging features of adult metanephric stromal tumor with BRAF V600E mutation. (A) Computed tomography scan shows a slightly enhanced, well-defined, oval mass (white arrow), in the upper pole of the left kidney. (B) Magnetic resonance imaging demonstrates that the mass has low-signal intensity on T2-wighted imaging (white arrow).
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case_images: Computed tomography scan showed a focally low-enhancing, circumscribed, oval mass in the upper pole of the left kidney (Figure 1A). A subsequent magnetic resonance imaging revealed that the mass had iso-signal intensity on T1-weighted and low-signal intensity on T2-wighted with enhancement after contrast injection (Figure 1B).
case_images: Histological characteristics of adult metanephric stromal tumor with BRAF V600E mutation. (A) At low power, the tumor is non-encapsulated and has an overall expansile contour. H&Ex15. (B) Subtly infiltrative border of the tumor with adjacent normal renal parenchyma (arrows). H&Ex40. (C) Numerous entrapped native renal tubules are noted. H&Ex100. (D) The tumor is composed of bland, spindle- or stellate-shaped cells, set in a predominantly collagenous and focally myxoid stroma. H&Ex100. (E) The highly hyalinized stroma encircles and entraps native renal tubules (arrows). H&Ex300. (F) The tumor induces angiodysplasia within entrapped blood vessels (arrow). H&Ex300.
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case_images: f2
case_images: Histologically, the tumor had overall expansile but focally infiltrative, scalloped margins, and numerous entrapped native renal tubules were noted throughout the tumor (Figures 2A -C). The tumor was composed of hypocellular, bland-appearing, ovoid- to spindle- or stellate-shaped cells, set in a predominantly collagenous and focally myxoid stroma (Figures 2D -F). Frequently, the highly hyalinized stroma surrounded entrapped native renal tubules or blood vessels forming concentric collarettes-like structures (Figure 2E). Occasionally, small-sized arterioles showing angiodysplasia were observed (Figure 2F).
case_images: Immunohistochemistry of adult metanephric stromal tumor with BRAF V600E mutation. The tumor cells are diffusely and strongly positive for CD34. x100.
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case_images: By immunohistochemistry, the neoplastic cells were diffusely positive for CD34 (Figure 3), and focally positive for estrogen and progesterone receptors; they were negative for PAX8, S100 protein, STAT6, MUC4, cytokeratin, WT1, and actin.
case_images: Fluorescence in-situ hybridization analysis is negative for rearrangements of both the (A)
  EWSR1 (x1500, arrows indicate fused green and orange signals) and (B)
  FUS (x2000, arrows indicate fused green and orange signals) loci (Insets in A and B indicate schematic diagram of break-apart probes flanking EWSR1 and FUS, respectively). (C) Targeted next-generation sequencing discloses the pathogenic mutation of BRAF exon15: c.1799T>A (p.V600E) in the tumor, as illustrated by the Integrative Genomics Viewer screenshot.
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case_images: Fluorescence in-situ hybridization analysis revealed negative for rearrangements involving both the EWSR1 and FUS loci (Figures 4A , B). Genetic testing using targeted next-generation sequencing for 425 cancer-relevant genes (GENESEEQ PRIME) disclosed the pathogenic mutation of BRAF exon15: c.1799T>A (p.V600E) in the tumor (Figure 4C).