PMC7594836_01
(a) CECT abdomen and pelvis transverse section (Case 1) showing right renal mass, compressing medially the right renal vein, ureter, and IVC with sectoral contact of about 180  with no apparent tumor thrombosis. (b) CECT thorax and coronal abdomen section (Case 2) revealed that left renal mass lesion with enhancing tumor thrombus extending up to the supradiaphragmatic IVC. (c) Plain MRI abdomen coronal section (Case 3) showing well-defined lobulated mass lesion with IVC thrombosis extending into the suprarenal IVC, below the diaphragm. (d) MR urography transverse section (Case 4) showing a well-defined mass of size 8 x 6 cm involving the renal pelvis, compressing IVC anteriorly. IVC, inferior vena cava; CECT, contrast-enhanced computed tomography.
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F1
Three of the cases had nonspecific imaging findings and were thought to be Renal cell carcinoma (RCC) provisionally (Figures 1a, b, and c). Magnetic resonance (MR) urography of this case (Figure 1d) showed a heterogenous well-defined mass lesion of 8 x 6-cm size predominantly iso-intense in T2 and iso to hypo-intense in T1 with restricted diffusion, involving renal pelvis of the right kidney and anteriorly compressing IVC with focal loss of the fat plane.
Intra-operative pictures of Case 4. (a) Showing tumor specimen of size 12.5 x 8 x 4 cm involving renal pelvis with grossly hydronephrotic right kidney. (b) Showing post-nephroureterectomy right renal bed with repaired IVC after excising involved cuff. IVC, inferior vena cava.
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F2
Intraoperatively, in the case of renal pelvis tumor, dense desmoplastic adhesions with IVC were found along the entire length of the mass (Figures 2a and b).
Histopathology and immunohistochemistry of case 4. (a) Showing (Hematoxylin-Eosin staining) small uniform round cells with a hyperchromatic nucleus and mild to moderate pale staining cytoplasm and pseudo-rosettes (20x). (b) Small round cells CD-99 IHC positive (20x). (c) Small round cells, FLI-1 positive (20x).
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F3
At places, the tumor cells were arranged in pseudo rosettes (Figure 3a). On IHC, we have consistently found CD-99 in all cases (Figure 3b), FLI-1 in three (75%) cases (Figure 3c), and vimentin in one (25%) case. Provisionally diagnosed case of upper tract TCC was confirmed to be ES/PNET of renal pelvis origin along with the presence of infiltration of the ureter (Figures 3a, b, and c).