FIGURE 5.

A 43-year-old man with desmoid-type fibromatosis in the mediastinum with recurrence (Group 1). This was misdiagnosed as a neurogenic tumor and as fibrosarcoma on preoperative CT and MR, respectively. (A) The contrast-enhanced axial CT image (5-mm reconstruction) shows a lobulated, well-defined mass (^∗) with mild homogeneous enhancement in the left posterior mediastinum. The difference in Hounsfield units between pre- and postenhancement is 7. Note the osteoblastic change of the rib (white arrow) and the neural foraminal widening (black arrow). (B) The tumor shows strong heterogeneous enhancement on an enhanced T1-weighted image. Note the internal nonenhancing low signal bands (white arrows) and internal signal voids (black arrows). (C) Grossly, an ill-defined irregularly-shaped firm mass is present. The cut surface of the mass glistens, and is whitish gray, coarsely trabeculated and partly myxoid, without hemorrhage and necrosis. (D) Tumor cells infiltrate the chest wall muscle (white arrows, ×40 magnification) and (E) also the marrow space of the rib (^∗, ×100 magnification). CT = computed tomography, MR = magnetic resonance.