患者男,20岁,右膝关节疼痛半年余,近期加重。查体:右膝关节活动正常,股骨下端局部未触及包块,皮温不高,表面无曲张的血管,稍压痛。X线片:右股骨下端内侧可见偏心性低密度区,病变内缘骨质硬化增厚,外缘骨皮质变薄,轻度膨胀,未见中断(图1)。CT检查:右股骨下端骨皮质下见一约3.0cm Male patient, 20 years old, right knee pain more than six months, the recent increase. Physical examination: right knee activity is normal, the lower part of the femur did not touch the mass, skin temperature is not high, the surface of varicose veins, a little tenderness. X-ray film: the right lower femoral medial can be seen eccentric low density area, the lesion edge of bone hardening thickening, cortical bone thinning, mild swelling, no interruption (Figure 1). CT examination: the right femoral cortical bone see about 3.0cm