PMC7532426_01
Computed tomography findings. (a) A plain axial section. The tumor was mainly composed of adipose tissue with thick irregular septum-like structures. (b) A contrast-enhanced axial section. The septum-like structures showed early enhancement. (c) A contrast-enhanced coronal section. There was no beak sign or sharp beak shape arising from the kidneys.
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Contrast-enhanced computed tomography (CT) revealed a tumor measuring 9 cm in the longest diameter surrounding the right kidney (Figure 1).
Magnetic resonance imaging findings. (a) Fat-suppressed T1-weighted scans. The tumor was mainly composed of a homogenously low-intensity area, including a weakly high-intensity area with thick irregular septum-like structures. (b) Dynamic contrast-enhanced image. The septum-like structures showed strong enhancement. There was no beak sign or sharp beak shape arising from the kidneys. (c) Coronal section of dynamic contrast-enhanced image. The tumor surrounded the right kidney with no beak sign.
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On fat-suppressed T1-weighted magnetic resonance imaging (MRI), the tumor had a homogenously low-intensity area containing a weakly high-intensity area with a thick irregular septum-like structure (Figure 2(a)) exhibiting strong enhancement (Figure 2(b)).
Histopathological findings. (a) Hematoxylin-eosin stain (x40). The tumor consisted of mature adipose tissue, smooth muscle cells, and thick-walled abnormal vessels. (b) Immunostaining for HMB45, a marker of angiomyolipoma, was positive in the tumor cells (x200).
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Histopathological examination revealed a heterogeneous tumor consisting of mature adipose tissue, spindle and epithelioid smooth muscle cells, and abnormal thick-walled blood vessels (Figure 3(a)). Immunohistochemically, the tumor cells tested strongly and diffusely positive for HMB45 (Figure 3(b)).