82-year-old female presents with a 3-month history of a rapidly enlarging mass in her right thigh Figs. 1, 2, 3, 4 and 5.

Fig. 1
figure 1

a Axial T1W FSE MR image. b Coronal STIR MR image

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Fig. 2
figure 2

Axial T1W FS post gadolinium image

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Fig. 3
figure 3

Static ultrasound image with Doppler flow

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Fig. 4
figure 4

Histopathological micrograph [4× magnification haematoxylin and eosin stain (4× H&E)]

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Fig. 5
figure 5

Axial PDW image performed 21 months after the index MRI scan

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