Chondrosarcomas in children and adolescents

Overview

This review by Puri, published in EFORT Open Reviews in 2020, covers chondrosarcoma in children and adolescents. These tumours are uncommon, making up under 5% of all chondrosarcomas, and there are few studies of extremity chondrosarcoma in young patients. The pelvis is the most common site, followed by the proximal femur. Chondrosarcoma is much rarer than osteosarcoma or Ewing sarcoma in young people: a Finnish study of patients under 18 found 0.3 chondrosarcomas per million compared with 3.6 osteosarcomas.

Types and diagnosis

Primary (central) tumours arise in previously normal bone, while secondary tumours arise from an osteochondroma or an enchondroma, at about 26 to 29% in most series of young patients. The risk of malignant change is under 1% in a solitary osteochondroma but about 5% in multiple osteochondromatosis, and it may reach 40% in Ollier disease and Maffucci syndrome. Grading is based on cellularity, nuclear features and mitoses. Under the 2013 WHO classification, Grade I is called an atypical cartilaginous tumour and considered an intermediate tumour. Differentiating enchondroma from Grade I chondrosarcoma is hard, and doctors often disagree, so these lesions should be discussed at a multidisciplinary meeting with a radiologist and a pathologist specialising in bone tumours. Mesenchymal chondrosarcoma is an aggressive subtype, making up 2 to 10% of all chondrosarcomas.

Staging and treatment

Staging includes radiographs and MRI of the area, and a CT of the chest. The need for a bone scan in every patient is questioned, and PET-CT is being studied to help separate grades. Chondrosarcoma is resistant to chemotherapy and relatively radioresistant, so surgical excision is the only reliable treatment. Wide resection is recommended for Grade II and III tumours and for pelvic and sacral lesions, while selected extremity Grade I tumours may be treated with extended intralesional curettage. Chemotherapy may have a role in mesenchymal chondrosarcoma, and radiotherapy is mainly used for unresectable lesions or incomplete resection. Reconstruction after resection is difficult in growing bones because of limb-length discrepancy.

Prognosis and surveillance

Recurrence and prognosis relate directly to the adequacy of resection, and outcomes in the young appear to be no different from those in adults. Patients with osteochondromas or enchondromas at higher-risk sites should be told to report pain or growth, and annual clinical examination with whole-body MRI may benefit selected patients.