Sometimes called Codman's tumor, a chondroblastoma is a rare type of benign bone tumor that originates from cartilage. Cartilage is the specialized, gristly connective tissue that is present in adults and the tissue from which most bones develop. Cartilage plays an important role in the growth process. There are many different types of cartilage that are present throughout the body. Chondroblastoma most often affects the ends of the long bones in the arms and legs at the hip,
shoulder, and knee. Chondroblastoma occurs when a single chondroblast (cell that produces cartilage) abnormally divides out of control. Why this occurs is unknown. There is apparently no association between chondroblastoma and repeated trauma.
Chondroblastoma is a rare type of bone tumor that can affect people of all ages. It is usually found in the epiphyses of long bones before epiphyseal closure. They are found in the secondary centers of ossification and account for 5% of benign bone tumors. Tumors are most likely found in the humerus, followed by the femur and then the tibia. Chondroblastomas may be found in association with aeurysmal bone cysts. Males are slightly more at risk and the diagnosis is usually made in persons from 5 to 25 years old. Chondroblastoma is, however, most common in children and young adults between the ages of 10 and 20 years. This type of tumor is also more common in males than females.
Symptoms of chondroblastoma may vary depending on the location of the tumor. However, each individual may experience symptoms differently. Chondroblastomas usually present as pain in the adjacent joint to the tumor associated with joint pain and swelling. The symptoms are usually present over a long period of time before the diagnosis is made. This presentation is often mistaken for chronic synovitis. A joint effusion may be detected on physical exam. The symptoms of chondroblastoma may resemble other medical conditions or problems. Always consult your physician for a diagnosis.
Curettage is the treatment of choice. The lesion must be well visualized, which usually requires the opening of the joint capsule. The defect is packed with bone graft. These tumors are radiosensitive, but radiation should only be used in complicated cases due to a risk of malignant transformation. After curettage, sometimes the remaining cavity is packed with donor bone tissue (allograft), bone chips taken from another bone (autograft), or other materials depending on the preference of the surgeon. During the operation, doctors will take a tissue sample of the tumor so the diagnosis can be confirmed under a microscope. If the tumor is located in the pelvis or some other sites, the operation may involve en bloc resection, which is the surgical removal of bone containing the tumor, rather than curettage. Internal fixation, with pins, may be required to restore the structural integrity of the bone. Phenol and liquid nitrogen should not be used due to possible disruption of the growth plate or articular cartilage damage. Rate of recurrence is 10-30%.