Question:

A 77-year-old female presented with a 3-week history of left thigh swelling and pain. There was no history of trauma (Figs. 1 and 2).

Fig. 1
figure 1

MRI of the left thigh. a Coronal STIR, b sagittal T2W FSE, c axial PDW FSE and d axial PD SPAIR MR images

Fig. 2
figure 2

US images of the left mid-thigh. a Transverse image with colour Doppler at the time of initial biopsy (no increased vascularity was evident and the colour Doppler activity seen on this image was artefactual) and b longitudinal image 2-weeks later