case_images: PMC9709104_01
case_images: Computed tomography of the kidney. (A) Abdominal pelvis CT scan shows a mass in the left kidney. There is a no dular mass of about 4 x 3.3 x 3 cm in the middle and lower pole of the kidney. (March 13, 2021). (B) Contrast-enhanced CT shows heterogeneous enhancement in the cortical phase (March) 13, 2021).
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case_images: PMC9709104_01_fonc-12-1045238-g001.jpg
case_images: f1
case_images: Figure 1 , a computed tomography (CT) scan of the abdomen and pelvis in March, 2021, showed a mass-like high density shadow arising from the anterior cortex, beside the left renal pelvis, about 4.1 x 4.5 cm in size, well-demarcated, with benign features. For example, the tumor tissue showed no invasion into peripheral structures, especially the renal vessels and peri-renal adipose tissue.
case_images: Pathological examination with hematoxylin-eosin stain. (A) The tumor tissue has a clear boundary with the intact parenchymal issue (x40). (B) The tumor tissue contains compactly arranged cells a nd blood vessels of different shapes (x100). (C) Spindle tumor cells row with benign patterns (x400).
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case_images: PMC9709104_01_fonc-12-1045238-g002.jpg
case_images: f2
case_images: A mass of the normal tissue from the parenchyma is attached to the tumor tissue for comparison.  Figure 2A  shows that the tumor tissue is clearly demarcated from the normal renal tissue. On magnification of the tumor tissue in  Figure 2B , we find that the tissue loses the normal microscopic structure of a renal tissue. Under x400 magnification ( Figure 2C ), the tumor cells were spindle-like with ovoid nuclei, small nucleoli, lightly-stained cytoplasm, and unclear boundaries.
case_images: Immunohistochemical staining. (A) STAT6(+) (x100), (B) CD34(+)(x100), and (C) normal renal tissue in the left part: CKpan(+); tumor tissue in the right part: CKpan(-)(x100).
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case_images: f3
case_images: As shown in  Figure 3 , STAT6(+) and CD34(+) have diagnostic significance.
case_images: The outcome of genetic testing with GRCh37/hg19 genome for reference. (A) The normal gene sequence for contrast. (B) The patient's gene: gene orders in the gray part are in accordance with (A) sequence and faulty orders are highlighted in different colors (C) A simple diagram of chromosome No. 12, which was thought to be broken in two sites and fused together so that the NAB2-STAT6 mutation came into being.
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case_images: PMC9709104_01_fonc-12-1045238-g004.jpg
case_images: f4
case_images: As shown in  Figure 4 , mRNA was reverse transcribed into DNA; we found that chromosome 12 harbored NAB2 (NGFI-A binding protein 2)-STAT6 fusions, which was located in the NAB2: exon 6:STAT6: exon 16 (accounted for 94.4%) by contrasting with a template strand of STAT6 mRNA.