All radiographs, computed tomography (CT), magnetic resonance imaging (MRI), bone scans, and positron emission tomography (PET) scans during the duration of treatment were reviewed by two radiology trainees (WA, SS), and imaging features of VIP were confirmed by a board-certified musculoskeletal radiologist (TL). VIP lesions were initially diagnosed and best characterized on radiographs and CT studies which were used for morphological analysis of the lesions. Standard radiographs were obtained of various bones and joints in at least two planes. CT studies of the chest were obtained on three different scanners-General Electric (GE) LightSpeed VCT, GE Discovery CT750 HD, and Phillips Brilliance 64-using the acquisition parameters listed in Supplementary Table 1.
The length, location in the body, location in the bone, type, and morphology of VIP lesions were recorded. The lesion type was classified as either continuous or interrupted. Lesions were further subclassified based on morphology as eggshell, lobulated, soap bubbles, solid, single layer, multilayered, spiculated or sunburst for continuous-type lesions and wedge-shaped, Codman triangle, interrupted onion skins, or interrupted spiculae for interrupted-type lesions [14] . Representative lesions are included in Figs. 1 and2.
The length, location in the body, location in the bone, type, and morphology of VIP lesions were recorded. The lesion type was classified as either continuous or interrupted. Lesions were further subclassified based on morphology as eggshell, lobulated, soap bubbles, solid, single layer, multilayered, spiculated or sunburst for continuous-type lesions and wedge-shaped, Codman triangle, interrupted onion skins, or interrupted spiculae for interrupted-type lesions [14] . Representative lesions are included in Figs. 1 and2.