PMC9681011_01
Abdominal MRI showing the mass compressing the right renal pelvis and ureter, and the right renal arteriovenous and inferior vena cava were also slightly compressed. (A) T1WI, low signal similar to the abdominal aorta (arrow). (B) T2WI, high signal for tumor (arrow). (C) Contrast-enhanced scan revealing that the tumor had an obvious enhancement with a central hypointense area (small arrow heads), and the filling of the contrast agent from the edge to the center was delayed. (D) DWI, high signal for the tumor (arrow).
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T2WI and DWI. The multiphase enhanced scan showed that the tumor had obvious enhancement with a central hypointense area, and the filling of the contrast agent from the edge to the center was delayed. The mass compressed the right renal pelvis and ureter, and the right renal arteriovenous and inferior vena cava were also slightly compressed ( Figure 1 ).
The gross specimen shows a well-defined solid mass of a white and brown color, and the cut surface was slightly jelly like.
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The cut surface was slightly jelly like with a medium texture, and the boundary was still clear ( Figure 2 ).
Microscopic findings of the renal hilum tumor. (A) Paraffin section showing the mass with lobulated capillaries (original magnification x100). Immunohistochemistry showing diffuse strong positivity for (B) CD31, (C) CD34, and (D) Fli1.
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Microscopically, there were lobulated capillaries covered by a monolayer of endothelial cells, red blood cells in the lumen, no smooth muscle fibers in the perivascular wall and no fibrous connective tissue between the vessels ( Figure 3A ). Pan (-), Melan-A (-), and EMA (-). Positive immunohistochemical results are shown in  Figure 3 .