Pediatric Osteochondroma

  • Etiology: benign bony growth covered by cartilage cap caused by piece of growth plate separates + lays down cartilage off of normal axis of development
  • Imaging: cartilage-capped bone projection, location usually is metaphysis of tubular long bones or costochondral junction (metaphyseal equivalent), sessile or pedunculated cystic growth on bony stalk / excresense away from metaphysis / growth plate
  • US: cartilaginous cap is hypoechoic with internal echogenicity similar to normal epiphyseal cartilage
  • Complications: 1-2% degenerate into chondrosarcoma
  • Clinical: presents as hard, mobile mass, pain may be due to nerve impingement, bursitis, vascular compression, most common benign bone tumor

Radiology Cases of Osteochondroma

Radiograph of multiple osteochondromas of the knee
AP radiograph of the knees shows bilateral lesions arising from the medial aspect of each tibial metaphysis, with a bony stalk growing away from the metaphysis with a lytic lesion growing at the tip of each stalk with a narrow zone of transition and no associated periosteal reaction.
CXR and CT of osteochondroma of the rib
CXR PA shows a calcific density in the head of the left third rib. Contiguous images from an axial CT without contrast of the chest shows a bony outgrowth at the proximal aspect of the left third rib posteriorly.