Giant cell tumor (GCT) is a bone tumor at the benign-malignant border, typically located in the epiphysis of long bones and showing locally aggressive behavior. It characteristically occurs in skeletally mature young adults (20-40 years), with the distal femur, proximal tibia, and distal radius being the most commonly affected sites. Radiologically, it is recognized by epiphyseal location, extension to subchondral bone, geographic destruction pattern, and absence of matrix mineralization. Local recurrence rate is high and it can rarely metastasize to the lungs.
Age Range
20-45
Peak Age
30
Gender
Female predominant
Prevalence
Uncommon
Giant cell tumor contains neoplastic stromal cells and reactive multinucleated osteoclast-like giant cells; neoplastic stromal cells express RANKL (receptor activator of nuclear factor kappa-B ligand) and this RANKL stimulates differentiation of osteoclast precursors into giant cells. Giant cells cause bone resorption through osteoclastic activity and this aggressive bone resorption manifests radiologically as geographic lytic destruction without matrix mineralization. The tumor begins growing in the epiphysis and extends to the subchondral bone — this subchondral extension is radiologically seen as the lesion continuing to the articular surface and is the most important location feature of giant cell tumor. On MRI, tumor tissue shows low-to-intermediate signal on T2-weighted sequences due to hemosiderin deposition — this low signal results from the superparamagnetic effect of hemosiderin and is an important distinguishing feature from the high T2 signal of cartilage tumors. Secondary aneurysmal bone cyst (ABC) components may develop within the tumor and fluid-fluid levels are seen in these areas.
Geographic lytic lesion extending to subchondral bone in the epiphysis of distal femur or proximal tibia in a skeletally mature young adult (20-40 years), without matrix mineralization and with non-sclerotic borders — together with absence of aggressive periosteal reaction, this is the most pathognomonic radiological appearance of giant cell tumor.
Epiphyseal, geographic pattern lytic bone lesion extending to the subchondral bone. Lesion margins are well-defined but without typical sclerotic rim (non-sclerotic border). No matrix mineralization (osteoid or chondroid). This finding, also visible on conventional radiography, is evaluated in more detail on CT for the lesion's relationship with cortex, pathological fracture risk, and soft tissue extension. The lesion may show eccentric location and may thin and expand the cortex.
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Epiphyseal geographic lytic lesion with non-sclerotic borders extending to subchondral bone, without matrix mineralization.
The tumor shows low-to-intermediate signal intensity on T1-weighted sequences. Areas with hemosiderin deposition show local signal decrease. The high T1 signal of normal fatty bone marrow is lost with tumor infiltration. T1 sequence is important for evaluating tumor invasion into articular cartilage and joint space.
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Epiphyseal mass with low-to-intermediate signal intensity on T1-weighted sequences with areas of hemosiderin deposition noted.
Solid components of the tumor show low-to-intermediate signal intensity on T2-weighted sequences — this feature results from the superparamagnetic effect of hemosiderin deposition. Low T2 signal is a very important feature of giant cell tumor in differential diagnosis because most other bone tumors (chondroid tumors, cystic lesions) show high T2 signal. If secondary aneurysmal bone cyst component is present, high T2 signal with fluid-fluid levels is seen in these areas.
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Low-to-intermediate signal intensity in solid components on T2-weighted sequences, consistent with hemosiderin deposition; giant cell tumor should be primarily considered.
Moderate diffusion restriction is seen in solid tumor components on DWI. ADC values are intermediate. Secondary aneurysmal bone cyst components do not show diffusion restriction. DWI may be helpful in treatment response assessment (after denosumab therapy) and detection of local recurrence.
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Moderate diffusion restriction in solid components on DWI; hemosiderin artifacts should be taken into consideration.
Solid tumor components show avid homogeneous enhancement on post-gadolinium sequences. The tumor's rich vascularity (many thin-walled capillaries) causes intense enhancement. In aneurysmal bone cyst components, enhancement is limited to septa and peripheral wall; cyst content does not enhance. Contrast-enhanced MRI plays a critical role in distinguishing solid from cystic components and determining the full extent of the tumor for surgical planning.
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Avid homogeneous enhancement in solid components on post-contrast sequences with non-enhancement in cystic/hemorrhagic areas.
The tumor thins and expands the cortex as it grows but typically does not produce aggressive periosteal reaction (sunburst, onion-skin). This feature is distinguishing from malignant bone tumors. In advanced cases, cortex may be completely destroyed and soft tissue extension may be seen. Pathological fracture risk increases as cortex thins — CT is the best modality for assessing this risk.
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Cortical thinning and expansion adjacent to the lesion without aggressive periosteal reaction.
Criteria
Most common form. Locally aggressive but histologically benign. Epiphyseal location, subchondral extension. Local recurrence rate 15-50% after curettage, 5-10% after wide resection.
Distinct Features
Typical epiphyseal geographic lytic lesion. Low-to-intermediate T2 signal (hemosiderin). Avid homogeneous enhancement. No matrix mineralization. No aggressive periosteal reaction.
Criteria
Secondary ABC development within GCT. Seen in 10-15% of cases. Fluid-fluid levels accompany solid GCT component.
Distinct Features
Solid component (low T2 signal, hemosiderin) and cystic component (fluid-fluid levels, high T2) coexist on MRI. Solid component enhances on contrast MRI, cyst content does not. Distinction from primary ABC is made by the presence of solid enhancing component.
Criteria
Primary malignant GCT or malignant transformation after recurrence. Rare (5-10%). High-grade sarcoma histology. More aggressive radiological findings.
Distinct Features
More prominent cortical destruction and soft tissue mass. Periosteal reaction may be seen. Marked diffusion restriction on DWI. More rapid growth. Increased risk of lung metastasis. Comparison with prior images is critical when malignant transformation after recurrence is suspected.
Distinguishing Feature
Primary aneurysmal bone cyst consists of fluid-fluid levels without solid enhancing component. Giant cell tumor has a solid enhancing component (low T2 signal, hemosiderin) and the cystic component is secondary.
Distinguishing Feature
Chondrosarcoma produces chondroid matrix (arcs and rings calcification) and shows very high T2 signal (hyaline cartilage). Giant cell tumor shows no matrix mineralization and has low-to-intermediate T2 signal due to hemosiderin.
Distinguishing Feature
Simple bone cyst is metaphyseal (not epiphyseal), is a homogeneous cyst at fluid density without solid component. Giant cell tumor is epiphyseal, contains solid tumor tissue, and shows enhancement.
Distinguishing Feature
Pigmented villonodular synovitis (PVNS) is intra-articular synovial proliferation showing low T2 signal due to hemosiderin (similar to GCT). However, PVNS is joint-centered with late and secondary bone invasion; GCT is bone-centered, starting from the epiphysis.
Urgency
moderateManagement
Küretaj + adjuvan tedavi (kemik çimento, fenol, kriyoterapi) veya geniş rezeksiyon. Denosumab (RANKL inhibitörü) cerrahi öncesi tümör küçültmek veya inoperabl olgularda tedavi olarak kullanılır. Lokal nüks oranı yüksek olduğundan yakın takip gereklidir.Biopsy
NeededFollow-up
Cerrahi sonrası ilk 2 yıl 3-6 ayda bir MR ile lokal nüks takibi. Yılda bir akciğer grafisi/BT ile pulmoner metastaz taraması. Denosumab tedavisinde tedavi yanıtı MR (kontrastlanma, boyut) ve BT (sklerotik yanıt) ile izlenir. 5 yıldan sonra yıllık takip.Giant cell tumor is a locally aggressive bone tumor and accurate diagnosis with appropriate surgical treatment is critically important. Radiological-pathological correlation should be performed after diagnosis and a multidisciplinary approach (orthopedic oncology, radiology, pathology) should be adopted. Denosumab therapy is an effective option in inoperable or recurrent cases. Although rare, regular pulmonary screening is recommended due to the risk of lung metastasis. Local recurrence rate is 15-50% after curettage, making close MRI follow-up mandatory.
Giant cell tumor is a locally aggressive neoplasm with 15-25% recurrence rate. Rarely can metastasize to lungs (2-3%). Treatment involves curettage + adjuvant (PMMA/phenols) or en-bloc resection. Denosumab (RANKL inhibitor) is a newer treatment option.