Fig. (1) A 12-year-old boy with a solitary osteochondroma. Plain radiographs show a small lesion protruding from the bone, mimicking a bone spur at the proximal tibia (a) (left: antero-posterior view, right: lateral view). CT shows that the lesion is located at the medial posterior edge of the tibia (b) (top: axial view, bottom: coronal view). MRI shows continuity of bone marrow with the lesion (c) (top: T1 weighted image, middle: T2 weighted image, bottom: T2 weighted image with fat-suppression). 3-dimensional reconstruction using CT depicts the lesion (d: top). A photograph of a resected specimen (d: bottom). (Yellow arrows indicate the tip of the osteochondroma).