PMC3638507_01
Plain radiographs of the right leg. Radiolucent lesions with sclerotic contours in the diaphyses of the right femur (a) and the right tibia (b) and the epiphyses of the right knee (c).
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The lesions in the diaphyses of the right femur and the right tibia were distended causing the surrounding cortex to thin (Figure 1).
Technetium bone scintigram. Abnormal uptakes are shown in the diaphyses of the right femur and the right tibia and around the bilateral knees and ankles.
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Technetium bone scintigram showed increased uptake in the diaphyses of the right femur and the right tibia and the right pelvis and around the bilateral knees and ankles (Figure 2).
Magnetic resonance imaging (MRI) of the lesions in the distal epiphysis of the right femur and the proximal epiphysis of the right tibia. All lesions show a low signal intensity on a T1-weighted image (a) and a high signal intensity on a fat-suppressed T2-weighted image (b). The lesions were strongly enhanced by gadolinium ((c) T1-weighted images enhanced by gadolinium).
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On magnetic resonance imaging (MRI), the epiphyseal lesions of the distal femur and the proximal tibia showed a low signal intensity on T1-weighted images and a high signal intensity on fat-suppressed T2-weighted images, and the lesions were markedly enhanced by gadolinium (Figure 3). 
Microscopic findings of the excised lesion in the distal epiphysis of the right femur. Spindle cells grow in storiform pattern around haphazard bony trabeculae and fibrous tissue stroma. There is lack of osteoblast rimming surrounding the trabeculae. (hematoxylin and eosin staining; x400).
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The trabeculae consisted of immature woven bone, the form of which resembled "alphabet soup." There was lack of osteoblast rimming surrounding the trabeculae (Figure 4).
Plain radiographs of the right knee five years after the first surgery.
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There was no recurrence in the lesions in the diaphyses of the right femur and the right tibia, and the epiphyseal lesions of the distal femur and the proximal tibia showed no increase in size radiographically at the final follow-up examination (Figure 5).