Giant Cell Tumor of Bone
A usually benign but locally aggressive bone tumor
Quick Facts
- Type: Bone tumor (usually benign)
- Common sites: Near the knee, wrist, and shoulder
- Typical age: Young to middle-aged adults
- Behavior: Locally aggressive; can recur
Overview
A giant cell tumor of bone is an uncommon growth that develops at the end of a long bone, most often around the knee (the lower thigh bone or upper shin bone), the wrist, or the shoulder. It is named for the large, multi-nucleated cells seen under the microscope. The tumor is usually noncancerous (benign), but it is described as locally aggressive because it can grow, destroy nearby bone, and come back after treatment.
Most giant cell tumors appear in young to middle-aged adults after the skeleton has finished growing. In rare cases the tumor can spread to the lungs or, very rarely, become malignant. With proper treatment, however, the outlook for most people is good.
Symptoms
Symptoms develop gradually and often center on a joint, because the tumor tends to form at the end of a bone close to a joint.
- Pain near the affected joint, which may worsen with activity or at night
- Swelling or a visible lump over the area
- Reduced movement or stiffness in the nearby joint
- A sense of weakness in the limb
- A bone that breaks easily with little or no injury (pathologic fracture), sometimes the first sign
Because these symptoms overlap with many other joint and bone problems, imaging is needed to identify the cause.
Causes
The exact cause of a giant cell tumor is not known. It is not inherited in most cases and is not caused by injury, diet, or lifestyle. Researchers have found changes in certain bone cells that drive the tumor to overactively break down bone, but why this process begins in a particular person is unclear.
What is well understood is the tumor's biology: it contains cells that recruit and activate osteoclasts, the cells that normally remodel bone. The result is an area where bone is dissolved and replaced by tumor tissue, which is why these tumors can weaken and reshape the bone.
Risk Factors
- Age between roughly 20 and 40, when most cases occur
- A fully matured (closed-growth-plate) skeleton
- Rarely, a prior history of Paget's disease of bone in older adults
There are no proven preventable risk factors, and the tumor occurs in otherwise healthy people.
Diagnosis
Diagnosis combines imaging with a tissue sample:
- X-rays: Often show a clear, expanding lesion at the end of a bone with a thinned outer shell.
- MRI or CT scans: Define the exact size of the tumor, whether it extends into soft tissue, and how close it lies to the joint.
- Biopsy: A sample of the tumor is examined under the microscope to confirm the diagnosis and rule out cancer.
- Chest imaging: Sometimes done because, rarely, these tumors can spread to the lungs.
Treatment
Treatment aims to remove the tumor completely while preserving the limb and joint as much as possible.
- Surgery (curettage): The most common approach, in which the tumor is scraped out and the cavity is treated and filled with bone graft or bone cement to reduce the chance of return.
- Wider resection: For large or recurrent tumors, more of the bone may be removed and reconstructed.
- Medication: A targeted drug that blocks bone breakdown (denosumab) may be used to shrink tumors that are difficult to remove or to make surgery safer.
- Radiation: Reserved for tumors that cannot be operated on, as it carries some long-term risk.
Because giant cell tumors can recur, regular follow-up imaging is an important part of care for several years after treatment.
Prevention
There is no known way to prevent a giant cell tumor, since its cause is not understood and it is not linked to lifestyle. The most useful step is early evaluation of persistent bone or joint pain and swelling, so that a tumor can be found and treated before it weakens the bone enough to fracture.
When to See a Doctor
See a doctor if you have ongoing pain or swelling near a joint that does not improve, especially if it wakes you at night or is accompanied by a lump. Seek prompt care if a bone breaks after minor or no injury, as this can be the first sign of a weakening tumor and needs urgent assessment.
Frequently Asked Questions
Is a giant cell tumor of bone cancer?
Most giant cell tumors are benign, meaning not cancer. However, they are locally aggressive and can destroy nearby bone and return after treatment. In rare cases they spread to the lungs or become malignant, which is why a biopsy and follow-up are important.
Where do giant cell tumors usually occur?
They most often form at the ends of long bones near a joint, especially around the knee, the wrist end of the forearm, and the shoulder. This location is why pain and swelling near a joint are common early symptoms.
Can a giant cell tumor come back after surgery?
Yes. Because the tumor can leave behind microscopic cells, it returns in a portion of cases, usually within the first few years. Filling the surgical cavity with bone cement and having regular follow-up imaging help detect any recurrence early.
How is a giant cell tumor treated?
The main treatment is surgery to remove the tumor, often by scraping it out and filling the gap with bone graft or cement. Large or hard-to-reach tumors may also be treated with a targeted bone medication, and follow-up scans monitor for return.
References
- National Cancer Institute (NCI). Bone Cancer.
- Mayo Clinic. Giant cell tumor of bone.
- MedlinePlus, U.S. National Library of Medicine. Bone tumors.
- American Academy of Orthopaedic Surgeons (OrthoInfo). Bone Tumors.