Chondroblastomas are benign, rare, yet aggressive tumors that typically grow at the ends of the body’s long bones, close to the epiphysis (joints). Chondroblastomas have been observed in the lunate5 triquetrum and hamate4. Although not malignant, chondroblastomas will grow if left untreated, possibly destroying surrounding bone and making movement painful. In extremely rare cases, the tumor can metastasize to the lungs or other organs. Delays in diagnosis result from the lack of typical clinical and radiologic presentation; findings in both cases are nonspecific. Surgery is always the preferred treatment, unless the tumor cannot be removed due to its location or size.
Pathophysiology
- The cause of chondroblastomas is not known.
- In children, they are thought to arise from the cartilaginous growth plates, just as the plates start to close.
- The tumors comprise many cells that resemble fetal cartilage.
- One hypothesis about the aggressive growth of chondroblastomas suggests an aneurysmal bone-cyst component.
- Chondroblastomas contain "coffee bean" shaped chondroblasts, multinucleated giant cells and a chondroid matrix5.
Related Anatomy
- A large percentage of chondroblastomas occur at the knee joint (34%), at the ends of the femur or tibia, or in the shoulder at the proximal humerus (20%).
- Less common locations include the pelvis, hip, and heel.
- In the shoulder, the chondroblastoma is called “Codman’s tumor.”
Incidence
- Chrondroblastomas are rare and account for only 1% of all bone tumors.
- Approximately 80% of patients are aged <25 years.
- Males are twice as likely as females to develop chondroblastomas.
- Chondroblastomas are extremely rare in the hand and wrist.
Differential Diagnosis
- Aneurysmal bone cyst
- Clear-cell chondrosarcoma
- Enchondroma
- Eosinophilic granuloma
- Giant cell tumor
- Infection of the bone (osteomyelitis)
- Osteoblastoma
