Imaging description

The principal role of imaging is in the management of aggressive fibromatosis, as well as staging in pre-operative planning and for the follow-up of progression in patients who are treated non-operatively. In post-operative follow-up imaging plays a key role in detecting recurrence. On conventional radiographs, aggressive fibromatosis is either undetectable or identified as an amorphous soft tissue mass. Calcification within the mass is uncommon. On rare occasions radiography may show bony infiltration or destruction of adjacent bones (Figure 83.1). As with most soft tissue tumors, MR is the best imaging modality for assessing aggressive fibromatosis. The majority of lesions appear iso- to mildly hyperintense relative to muscle on T1-weighted image. The T1 signal intensity is usually homogeneous. On T2-weighted images the majority of lesions are hyperintense relative to muscle (Figure 83.1). In about one third of the patients aggressive fibromatosis displays lower signal intensity than muscle on T2-weighted images (Figure 83.2). These lesions have less cellularity and more collagen than tumors with high signal-intensity T2-weighted images. The hyperintense lesions on T2-weighted images are typically heterogeneously hyperintense. Bands of low signal intensity within the lesion on all sequences are reported to occur in about two thirds of cases. This is in concordance with previously published data. After injection of IV gadolinium, these tumors show either avid or moderate enhancement.