Myositis Ossificans - Imaging
Image Description
Imaging Studies: The findings of myositis ossificans (MO) on plain radiographs, CT and MRI depend upon the stage and maturity of the lesion. MO in mature phase can often be diagnosed on plain radiographs. However, the diagnosis may be difficult in earlier stages due to the lack of bone formation.
Plain radiographs taken within 1-2 weeks after onset are normal or just show ill-defined soft tissue density. There may be periosteal reaction in the adjacent bone. Soft tissue calcifications appear by the 3rd to 4th week in the form of faint, amorphous and floccular opacities on plain films. As the lesion progresses, the soft tissue mass becomes well-defined and develops a peripheral eggshell-like layer of coarse calcifications by 6 to 8 weeks. Mature lesions are typically oriented along the long axis of the muscle and show a radiolucent gap between the lesion and the bone.The central part of the lesion remains uncalcified (or lightly calcified at most) and radiolucent.
Case History: 20 y/o male with injury to the right thigh two months ago. Plain radiograph (frontal view) shows an area of dense radio-opacity appearing like a 'sheath' noted on the right side adjacent to the femur. It appears denser than bone with irregular margins and is parallel to the long axis of the bone.
Case courtesy of Dr Aditya Shetty, Radiopaedia.org. From the case rID: 27674
Plain radiographs taken within 1-2 weeks after onset are normal or just show ill-defined soft tissue density. There may be periosteal reaction in the adjacent bone. Soft tissue calcifications appear by the 3rd to 4th week in the form of faint, amorphous and floccular opacities on plain films. As the lesion progresses, the soft tissue mass becomes well-defined and develops a peripheral eggshell-like layer of coarse calcifications by 6 to 8 weeks. Mature lesions are typically oriented along the long axis of the muscle and show a radiolucent gap between the lesion and the bone.The central part of the lesion remains uncalcified (or lightly calcified at most) and radiolucent.
Case History: 20 y/o male with injury to the right thigh two months ago. Plain radiograph (frontal view) shows an area of dense radio-opacity appearing like a 'sheath' noted on the right side adjacent to the femur. It appears denser than bone with irregular margins and is parallel to the long axis of the bone.
Case courtesy of Dr Aditya Shetty, Radiopaedia.org. From the case rID: 27674