Question

A slowly growing painless lump:

A 17-year-old girl developed a slowly growing painless lump in the right thigh region. No previous medical or trauma history of note (Figs. 1, 2 and 3).

Fig. 1
figure 1

Axial T1W TSE (a) and pre- (b) and post-contrast (c) fat suppressed T1W TSE MR images of the right thigh

Fig. 2
figure 2

a Transverse greyscale and b colour Doppler US images of the right thigh

Fig. 3
figure 3

Histology. H&E at a 60 × , b 120 × and c 280 × magnification