MRI of aggressive fibromatosis: Frequent appearance of high signal intensity on T₂-weighted images

Magnetic resonance imaging of seven patients with eight pathologically proven desmoid tumors tumors was performed and retrospectively reviewed. On T₂-weighted images, all but one lesion demonstrated increased signal intensity relative to muscle, and had signal intensity similar to that of fat. The signal was heterogenous in six of these seven lesions. In a patient with synchronous multicentric lesions, light microscopy correlation revealed increased cellularity in one lesion with increased signal intensity and dense collagenous elements in a second lesion, with decreased signal intensity. High signal intensity appears to be typical but nonspecific, and in following these patients could indicate recurrent tumor, superimposed inflammatory process or granulation tissue.