PMC3804818_01
Radiograph of the left knee depicting (A) anteroposterior, (B) lateral and (C) skyline view. There is a 1.7x2.4 cm radiolucent area in the medial patella. On MRI, patella lesion is hypointense on T1WI (D) and hyperintense on T2WI (E). Gadolinium-contrast shows a diffusely enhanced lesion in the medial patella (F).
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Periosteal reaction was absent (Figure 1A-C). T2WI, which was diffusely enhanced after gadolinium-contrast administration. The tumor was composed of multiple cavities, and fluid level was observed in each compartments. There was no obvious invasion to the adjacent muscle or joint (Figure 1D-F).
A) Under the microscope, the tumor was a giant cell lesion with fragmented bones and fibrosis, hemosiderin deposits and mild infiltration of chronic inflammatory cells (H&E stain); B) Monocytes of the lesion was short spindle-shaped and slightly positive with S-100 staining.
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In limited areas, there were monocytes that were short spindle-shaped and slightly positive with S-100 staining, which was consistent with chondroblastoma (Figure 2A,B).
Radiograph at 9 months follow-up. A) Anteroposterior, B) lateral and C) skyline views of the knee. The artificial bone graft is seen in the cavity and no evidence of recurrence or arthritic change is present.
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During his 9 months follow-up, no recurrence or arthritic change of the knee has developed (Figure 3A-C).