Mobile primary renal vein lipoma with an accelerated growth pattern

Figures

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  Fig 1. Imaging findings of the primary intravascular lipoma. A, Initial contrast-enhanced computed tomography (CT) scan showing a coronal section of a homogenous low-density tumor within the left renal vein (white arrow) with its origin (yellow arrow). A left renal cyst (red arrowhead) can also be seen. B, View of intravascular lipoma growing into the inferior vena cava (IVC; yellow arrow) on initial contrast-enhanced CT scan. C, Initial magnetic resonance image showing a fat-attenuating mass extending into to the perihepatic IVC (white arrow). D, Follow-up magnetic resonance venography showing extension of the mass into the inferior cavoatrial junction (white arrow).

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  Fig 2. A, Photograph of resected tumor fragments measuring ∼10 cm long. Black arrowhead indicates portion facing the renal vein; and white arrowhead, the portion facing the inferior vena cava (IVC). B,C, Photomicrograph of hematoxylin and eosin–stained histologic section confirming the diagnosis of lipoma (original magnification ×200). Black arrowheads indicate areas of calcification. C, Photomicrograph of hematoxylin and eosin–stained histologic section showing mature adipocytes (original magnification ×200).