case_images: PMC9890403_01
case_images: Contrast-enhanced CT scan of the abdomen and pelvis. (a, b) Coronal portovenous contrast enhanced abdominal CT scan, (c) Axial T1-weighted VIBE sequence fat-saturated post contrast, (d) Grey scale and (e) color Doppler ultrasound images demonstrate a heterogeneous mass (curved arrow) in the right renal pelvis (a) with an apparent direct extension through the right renal vein into the IVC (b, c, d) with no internal vascularity (e) (arrow).
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case_images: PMC9890403_01_cureus-0015-00000033244-i01.jpg
case_images: FIG1
case_images: The results were suggestive of a bland thrombus (Figure 1).
case_images: Intravenous biopsy of the thrombus. Trans-jugular biopsy of the caval mass/thrombus under direct transabdominal ultrasound (a) and fluoroscopic guidance (b) with insertion of a suprarenal IVC filter (asterisk) (c).
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case_images: PMC9890403_01_cureus-0015-00000033244-i02.jpg
case_images: FIG2
case_images: An intravenous biopsy of the thrombus was performed using a transjugular liver biopsy needle, and pathology confirmed the thrombus was an AML (Figure 2).
case_images: Right nephrectomy specimen. Gross photograph of the right nephrectomy specimen, illustrating: two large tumor masses (blue arrows, one near the renal pelvis and the other is exophytic at the upper pole), a tumor embolus at the renal vein margin (black arrow), and large number of small discrete intraparenchymal tumor nodules (green arrows).
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case_images: PMC9890403_01_cureus-0015-00000033244-i03.jpg
case_images: FIG3
case_images: Pathologic examination of the right radical nephrectomy specimen revealed two relatively large intraparenchymal renal masses (Figure 3).
case_images: Microscopic photo. Low magnification photomicrograph showing a tumor nodule (arrow) extending between renal cortical tissue (right upper) and pelvicalyceal system (lower central). Another tumor nodule is also seen (star). (H&E stain; original magnification 20x).
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case_images: PMC9890403_01_cureus-0015-00000033244-i04.jpg
case_images: FIG4
case_images: Microscopic examination revealed two large masses exhibiting triphasic smooth muscle cells (epithelioid to slightly spindly, with granular to clear cytoplasm), mature adipose tissue, and occasional thick-walled vessels (Figures 4-5).
case_images: Microscopic photo. HMB-45 immunohistochemical staining showing positive reaction in the tumor tissue noted in Figure 4. (original magnification 20x).
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case_images: FIG5
case_images: Microscopic examination revealed two large masses exhibiting triphasic smooth muscle cells (epithelioid to slightly spindly, with granular to clear cytoplasm), mature adipose tissue, and occasional thick-walled vessels (Figures 4-5).
case_images: Microscopic photo. High magnification photomicrograph illustrating various tumor components, including the smooth muscle cells (central and left), the fatty component (right), and a small vessel (arrow). (H&E stain; original magnification 200x).
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case_images: PMC9890403_01_cureus-0015-00000033244-i06.jpg
case_images: FIG6
case_images: An immunohistochemical study showed that the tumor cells were positive for HMB-45 and Mart-A (melan-A) markers but negative for Pax-8 (Figure 6).
case_images: Microscopic photo. Tumor thrombus (star) involving the renal vein (arrow) (H&E stain; original magnification 20x).
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case_images: FIG7
case_images: The tumor involved the renal vein (in a thrombus-like extension) and extended to the renal vein margin, reaching focally to the perinephric fat margin (Figure 7).
case_images: Microscopic photo. The neoplastic cells forming multiple small discrete intraparenchymal nodules (microhamartomas) (arrow on one of them). (H&E stain; original magnification 20x).
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case_images: PMC9890403_01_cureus-0015-00000033244-i08.jpg
case_images: FIG8
case_images: Small, discrete, intraparenchymal nodules noted grossly were microscopically formed of similar components as the two previously described larger masses, representing the so-called microhamartoma (Figure 8).