case_images: PMC10785724_01
case_images: Ultrasound images of the left kidney using the superficial probe, showing nephrogenic rests manifesting as well-defined hypoechoic (A) and isoechoic (B) nodules.
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case_images: An abdominal ultrasound was performed, showing a voluminous heterogeneous left renal mass, associated with multiple small and bilateral renal nodules, which exhibited an oval-shaped, hypoechoic and isoechoic homogeneous appearance, with no flow on color Doppler (Figure 1).
case_images: Axial CT scan image of the abdomen, showing the nephrogenic rests manifesting as small bilateral oval-shaped nodules, which are homogeneous with almost no enhancement (orange arrows), associated with a left nephroblastoma manifesting as a voluminous, round-shaped and heterogeneously enhanced mass of the lower pole of the left kidney (white arrows).
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case_images: A chest-abdomen-pelvis computed tomography (CT) was subsequently performed, showing the left voluminous renal mass, which exhibited a heterogeneous enhancement after contrast, in addition to the small bilateral oval-shaped intra and perilobar renal nodules, which displayed a hypodense appearance with a discrete homogeneous enhancement after contrast (Figure 2).
case_images: Axial MRI images, in T2-weighted sequence (A and B), ADC map (C), and post-contrast (D), showing the bilateral nephrogenic rests presenting as oval-shaped nodules, T2 hypointense (A, orange arrows) and T2 hyperintense (B, orange arrow), with low ADC (C, orange arrows) and no post-contrast enhancement (D, orange arrows). Associated with a left nephroblastoma presenting as a voluminous round mass, T2 hyperintense (B, blue arrows) with low ADC (C, blue arrows), and heterogeneous post-contrast enhancement (D, blue arrows).
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case_images: All of them exhibited diffusion restriction, and either a discrete or no enhancement after contrast, with a maximal diameter not exceeding 25 mm (Figure 3).
case_images: MRI images showing decrease in size of the nephrogenic rests: Pre-chemotherapy ADC map (A) versus post-chemotherapy (B), and pre-chemotherapy coronal T2 (C) versus post-chemotherapy (D). Also note a decrease in size of the nephroblastoma (blue arrows).
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case_images: Histopathologic examination images with routine stain, showing: Hyperplastic perilobar nephroblastomatosis manifesting a direct interface with normal renal parenchyma with no pseudocapsule (A, x10). Hyperplastic intralobar nephroblastomatosis with a direct interface with normal renal parenchyma (B, x10). Post-chemotherapy Wilms tumor with chemotherapy-induced changes with foamy macrophages (C, x4). Post-chemotherapy Wilms tumor of blastemal type (D, x4).
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case_images: The WT exhibited a predominant blastemal component, while the NRs, mainly hyperplastic, were observed in both intralobar and periloar regions, demonstrating a direct interface with normal renal parenchyma, devoid of a pseudocapsule (Figure 5).