Figure 7. Parosteal lipoma anterior to left femur. (a) A fatty, lucent mass can be seen associated with mature ossification and cortical thickening at the anteromedial aspect of the bone (arrows). (b) Axial T₁ weighted MR image shows fatty marrow within the ossified component (arrow), the homogeneously fatty mass and cortical thickening anteromedially. In this case, the periosteum has reacted to the parosteal location of the mass—there is no cortical breakthrough or involvement of the medulla.