A 22-years-old male presented with atraumatic painful thigh mass. The patient underwent contrast-enhanced CT (CECT), followed by PET-CT and finally MRI examination (Figs. 1, 2, 3, 4 and 5).

Fig. 1
figure 1

Axial non-contrast (upper axial images) and CECT (lower axial images) through the pelvis and the proximal thighs at the equilibrium phase. Coronal reformatted image of contrast-enhanced CT at the equilibrium phase (D)

Full size image
Fig. 2
figure 2

[FDG18] PET-CT through the pelvis and the proximal thighs. Axial (A, B), coronal and sagittal reformatted images (C, D)

Full size image
Fig. 3
figure 3

MRI through the pelvis and proximal thighs. Coronal T1-weighted fast spin echo (A), STIR (B), T2*-weighted gradient echo (C),sagittal T2-w 3D (D), axial T1-w gradient-echo out-of-phase and in-phase (E, F)

Full size image
Fig. 4
figure 4

MRI through the proximal thighs. Sagittal reformatted images of 3D T2-weighted spin echo (A, B), axial T2*-weighted gradient-echo (C) and axial reformatted image of 3D T2-weighted spin-echo

Full size image
Fig. 5
figure 5

Histopathological photomicrographs (hematoxylin and eosin staining) after biopsy of the sciatic nerve (A) and of the thigh lesion (B)

Full size image