Figure 16a. Aggressive fibromatosis in a 12-year-old girl with a previously diagnosed cervical mass that extended to the mediastinum. Coronal T1-weighted (900/15) (a) and T2-weighted (2,280/20) (b) MR images show a predominantly hypointense lesion that involves the left sternocleidomastoid muscle, surrounds the great vessels, and extends into the mediastinum (arrows). (Figs 16a and 16b reprinted, with permission, from reference 10.)