PMC5006721_01
Axial contrast-enhanced CT image (A) reveals a large right-sided renal mass and interaortocaval metastatic lymph nodes (arrow). Note the small bowel invasion (open arrow) which was surgically confirmed. The linear, focal enhancing structures, (arrow heads) represent the internal vasculature of the tumor. The large mass caused severe enlargement and distortion of the right kidney (B) with loss of differentiation of corticomedullary ultrastructure. Note the large tumoral implant (arrow in b) in the Gerota's fascia.
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The central solid components were moderately enhancing relative to the periphery of the tumor (Figure 1). Also CT examination revealed that the tumor had extended beyond the retroperitoneum and invaded a small bowel segment (Figure 1A), which was confirmed surgically. Additionally separate tumoral implants were noticed within the right perirenal tissue (Figure 1B).
The chest CT image reveals a metastatic right pulmonary nodule in the right lower lobe (arrow in A) and soft tissue (B) and bone window (C) images of the right parietal bone metastasis are shown in cranial CT.
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Metastatic lung nodules and calvarial metastasis were noticed upon further evaluation for staging of the disease (Figure 2).
Axial T1-weighted (A), fat suppressed T2-weighted (B) and fat suppressed postcontrast T1-weighted (C) images of the tumor demonstrate its heterogeneous and hemorrhagic (arrow in A) content. Notice the paraaortic metastatic lymph nodes (arrow in B) and heterogeneous enhancement and the increased perirenal vasculature due to rich feeding vessels within the perirenal fat tissue (arrow in C).
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On MRI, the hemorrhagic heterogeneous content of the tumor was readily appreciated on T1- weighted images, and the solid component appeared as hypointense to the striated muscle (Figure 3A). On T2 -weighted images the mass appeared as a heterogeneous lesion with a relatively high signal intensity (Figure 3B) and on postcontrast T1- fat suppressed images abundant feeding vessels in the perirenal fat and Gerota's fascia were seen (Figure 3C).
Coronal T2-weighted HASTE (A) and T1-weighted post-contrast subtraction images (B) showing the vascular displacement of the inferior vena cava (arrow).
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Also the vascular displacement of the abdominal aorta and inferior vena cava was well appreciated on coronal T2- weighted (Figure 4A) and post-contrast T1-weighted images (Figure 4B).
The mass shows marked diffusion restriction (A, B); notice a similar diffusion restriction in the metastatic retroperitoneal lymph node (arrow in C).
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ADC value of 0.64 (+-0.27)x10-3 mm2/s. A similar pathologic diffusion restriction was noticed in retroperitoneal lymphadenopathy, as well as retroperitoneal tumoral implants, reflecting hypercellularity and metastatic involvement (Figures 5, 6).
The diffusion weighted image with b=1000 s/mm2 (A) and corresponding ADC map (B) of the tumor depict the significant diffusion restriction of the retroperitoneal tumoral implants (arrow) and paraaortic lymph nodes (curved arrow), as salient as the tumor itself.
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ADC value of 0.64 (+-0.27)x10-3 mm2/s. A similar pathologic diffusion restriction was noticed in retroperitoneal lymphadenopathy, as well as retroperitoneal tumoral implants, reflecting hypercellularity and metastatic involvement (Figures 5, 6).
The tumor shows invasion of the renal parenchyma and perirenal fat (A, B). It is composed of uniform small round blue cells (C). Notice the occasional rosette formations (open arrows in C).
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Renal parenchymal, pelvicalyceal and sinusal infiltration, as well as perirenal fat and Gerota's fascia invasions were confirmed in histopathological evaluation of the surgical specimen (Figure 7A, 7B). Areas of rosette formation were also suggestive of PNET (Figure 7C).
Immunohistochemical analysis demonstrated CD 99 (A), Fli-1 (B) and synaptophysin (C) positivities. Note the ubiquitous Ki-67 expression, representing the high proliferation index (D).
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Immunohistochemically, the tumor showed synaptophysin, CD 99, Fli-1 positivities and 85% proliferation index with Ki-67 (Figure 8A-8D).