PMC4736802_01
Anteroposterior (a) and lateral-oblique (b) radiographs of the left leg showing ossification in the middle third of the leg (arrows), possibly located in the interosseous membrane.
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Radiographs showed a heterotopic ossification in the middle third of the leg (Figure 1).
Coronal CT scan of the leg (a) demonstrates that the ossification (arrow) is in the interosseous membrane. It is in continuity with the fibula but separated from the tibia by a thin nonossified zone. Axial CT scans (b and c) show separation of the ossification (arrows) from lateral border of the tibia.
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Computerized tomography (CT), performed to better determine the site and extension of the ossification, revealed that the lesion was located in the interosseous membrane and started from the left fibula but did not reach the lateral aspect of the tibia (Figure 2).
T2-weighted cross-sectional MR fat saturation sequence. The periosteum of the lateral margin of the tibia shows a hyperintense signal (black arrow) and hyperintense zones are visible in the lateral portion of the tibial diaphysis (white arrow).
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T2-weighted cross-sectional fat saturation sequences, a hyperintense signal on both the lateral aspect of the periosteum and lateral part of the tibial diaphysis at the level of the ossification (Figure 3).
Postoperative anteroposterior radiograph showing complete excision of the ossification.
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At 1-year follow-up, radiographs showed no recurrence of the ossification (Figure 4).
Low-power photomicrograph of the removed heterotopic ossification stained with hematoxylin-eosin showing mature lamellar bone (B) separated by medullary cavities (M) containing numerous areas of adipose tissue with expanded involution (arrows).
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The bone marrow exhibited expanded adipose involution and mild fibrosis (Figure 5), as it may occur in some cases of myositis ossificans.