Caption

Benign bone tumour (osteochondroma) below the knee of a 9-year-old girl. An osteochondroma grows from the side of a bone, usually at the end of the long bones near the knee or shoulder. Osteochondromas develop in late childhood and early adolescence and stop growing when the skeleton is fully developed. They are painless and only cause problems if they interfere with joint movement. However, as a small proportion of the tumours can become malignant they are usually surgically removed.