You are in: eMedicine Specialties > Radiology > MUSCULOSKELETAL Giant Cell TumorArticle Last Updated: Jun 27, 2007AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: Lesley-Ann Goh, MBBS, FRCR, Consultant, Department of Diagnostic Radiology, National University Hospital Coauthor(s): Wilfred CG Peh, MD, MBBS, FRCP(Glasg), FRCP(Edin), FRCR, MHSM, Clinical Professor, Faculty of Medicine, National University of Singapore; Senior Consultant Radiologist, Programme Office, Singapore Health Services; Tony WH Shek, MBBS, FRCPA, FHKCPath, FHKAM, Honorary Clinical Assistant Professor, Department of Pathology, University of Hong Kong Editors: Giuseppe Guglielmi, MD, Associate Professor of Radiology, Department of Radiology, Scientific Institute Hospital; Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand; Murali Sundaram, MBBS, FRCR, FACR, Consulting Staff, Department of Diagnostic Radiology, The Cleveland Clinic Foundation; Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute; Felix S Chew, MD, MBA, EdM, Professor, Department of Radiology, Vice Chairman for Radiology Informatics, Section Head of Musculoskeletal Radiology, University of Washington Author and Editor Disclosure Synonyms and related keywords: osteoclastoma, multinucleated giant cells, Paget disease, aneurysmal bone cysts, osteoclastlike giant cells INTRODUCTIONSection 2 of 10
  BackgroundGiant cell tumor of the bone is a relatively uncommon tumor that is characterized by the presence of multinucleated giant cells. This type of tumor is usually regarded as benign. In most patients, giant cell tumors have an indolent course, but they can recur locally in as many as 50% of cases. Metastasis to the lungs may occur. Cooper first reported giant cell tumors in the 18th century; in 1940, Jaffe and Lichtenstein defined giant cell tumor more strictly to distinguish it from other tumors. Giant cell tumors usually occur de novo but may also occur as a rare complication of Paget disease of the bone. PathophysiologyGiant cell tumor of the bone has a distinctive microscopic appearance, and its diagnosis is usually not difficult, despite the fact that the gross appearance of a giant cell tumor is less characteristic. The tumor is usually seen as a soft, brown mass; areas of hemorrhage, which appear dark red, and areas of collagen, which appear gray, may be observed. On cut sections, necrosis and blood-filled spaces are commonly seen. Intact resected specimens of giant cell tumor are rare because most patients are treated by curettage. Grossly, the curettage material is soft, friable, and dark brown. Although called giant cell tumor, the basic proliferating cell is the background mononuclear stromal cell, in which the characteristic osteoclastlike giant cells are uniformly distributed (see Image 1). The origin of these mononuclear cells is not fully known, but they are believed to be derived from primitive mesenchymal stem cells or cells of a histiocytic macrophage origin. Osteoclastlike giant cells have an identical nuclear morphology, presumably formed by the fusion of mononuclear stromal cells. Mononuclear cells commonly have a round or ovoid nucleus, but occasionally they can be spindle shaped. They possess a variable amount of eosinophilic cytoplasm. No intercellular matrix is produced by the mononuclear cells or the multinucleated giant cells. Mitotic activity is highly variable and of no prognostic significance. Similarly, the grade of a giant cell tumor of the bone has no prognostic significance. Although a typical giant cell tumor of the bone is easy to diagnose, a few histologic variants are commonly seen. Small foci of aneurysmal bone cysts are common in giant cell tumor (see Image 2). In rare circumstances, these foci may dominate the histologic features; therefore, thorough sampling for an underlying giant cell tumor is indicated. Occasionally, a giant cell tumor is composed predominantly of spindle cells and foam cells to the extent that no discernible osteoclastlike giant cells are found. Such tumors can be easily mistaken for benign fibrous histiocytoma or xanthoma (see Image 3). Again, if the clinical and radiologic impressions suggest a giant cell tumor, thorough tissue sampling of areas in which giant cell tumors typically occur is warranted; usually, a minute residual focus of giant cell tumor is found. Although giant cell tumor forms no intercellular matrix, foci of reactive bone formation can be seen, especially in tumors complicated by fracture. Areas of infarct are not uncommon in giant cell tumors. Intravascular tumor emboli may be found in the periphery of some giant cell tumors, but this finding does not appear to be correlated with its metastatic potential. Occasionally, an otherwise typical giant cell tumor of the bone can metastasize, usually to the lungs (see Image 4). Surprisingly, metastatic giant cell tumor does not have an ominous prognosis; patients can expect long-term survival after the metastases are surgically excised. Note that multinucleated osteoclastlike giant cells are not pathognomonic of giant cell tumor of bone. Osteoclastlike giant cells can be found in a wide variety of normal, reactive, benign, and malignant neoplastic conditions. Brown tumor in hyperparathyroid bone disease is an important nonneoplastic mimic of giant cell tumors. Hyperparathyroid bone disease is a generalized metabolic disease with increased serum calcium levels, whereas giant cell tumor is a localized disease; while the 2 can be histologically identical, they have different clinical presentations and radiologic appearances. Giant cell reparative granuloma is a benign reparative lesion that affects the small bones of the hands and feet. It is histologically similar to giant cell tumors of bone. Other primary bone tumors that contain osteoclastlike giant cells include chondroblastoma, chondromyxoid fibroma, and giant cell osteosarcoma. FrequencyInternationalGiant cell tumor of the bone accounts for 4-5% of primary bone tumors and 18.2% of benign bone tumors. The incidence is increased in patients with Paget disease of the bone, in which giant cell tumor is a rare neoplastic complication. Giant cell tumor is a rare complication compared with Paget sarcoma, which has an incidence of sarcomatous change of <5%. Mortality/Morbidity
Race
SexA slight female predominance is noted; approximately 50-57% of cases involve female patients. AgeTypically, giant cell tumors occur in skeletally mature patients aged 20-40 years. The incidence peaks in those aged 20-30 years.
AnatomyMost giant cell tumors (60%) occur in the long bones, and almost all are located at the articular end of the bone (see Image 5). Metaphyseal involvement may occur in skeletally immature patients. Common sites include the proximal tibia, distal femur, distal radius, and proximal humerus, although giant cell tumors have also been reported to occur in the pubic bone, calcaneus, and feet. Giant cell tumors may also occur in the vertebrae (see Image 6). Giant cell tumors are 3-4 times as common in the sacrum as they are in the rest of the spine. Sacral tumors may be so extensive that they involve the entire sacrum. Rarely, the tumor may extend across the sacroiliac joint to involve the adjacent ilium or may extend across the L5-S1 disk to involve the posterior elements of the L5 vertebra. The location of giant cell tumors within the spine can vary, and the most commonly involved areas are the vertebral body and the vertebral arch. Rarely, giant cell tumors develop in the ribs (see Image 7). Clinical DetailsGiant cell tumors typically occur in adults aged 20-40 years. Patients often complain of pain and swelling at the affected site. Pathologic fracture is present in 10% of patients (see Image 8). Vertebral giant cell tumors may extend into the spinal canal and compress the spinal cord, resulting in neurologic symptoms. Giant cell tumors are rarely multicentric (see Image 9). This condition should be considered when patients present with giant cell tumors in the hands, because the incidence of tumors in the small bones of the hand and sacrum is increased. Preferred ExaminationThe radiographic appearance of giant cell tumors is often characteristic. Magnetic resonance imaging (MRI) is sensitive for the detection of soft-tissue changes, intra-articular extension, and marrow changes. MRI is the best method for assessing subchondral breakthrough and extension of tumor into an adjacent joint. Its diagnostic accuracy is high, especially when MRIs are interpreted in conjunction with plain radiographs. Computed tomography (CT) scans and bone scans are usually less useful than other examinations. Limitations of TechniquesOn radiographs, typical giant cell tumors are usually easily distinguished from other bone tumors. Giant cell tumors are lytic, subarticular, and eccentric, and they are often lacking a sclerotic rim; however, unusual variants may make the radiographic diagnosis difficult. The disadvantages of MRI are its relatively high cost and limited availability. In addition, some patients experience claustrophobia during the examination and may require sedation. MRI is also contraindicated in patients with cardiac pacemakers, orbital foreign bodies, and noncompatible aneurysmal clips. DIFFERENTIALSSection 3 of 10
Aneurysmal Bone Cyst Chondroblastoma Hyperparathyroidism, Primary Other Problems to Be ConsideredTelangiectatic or fibrogenic variants of osteosarcoma
RADIOGRAPHSection 4 of 10
FindingsThe most important radiographic findings of giant cell tumor are the location of the tumor, its lytic nature, and the lack of a host response. Typically, giant cell tumors are expansile, osteolytic, radiolucent lesions without sclerotic margins and usually without a periosteal reaction. Septa may be seen in the lesion in 33-57% of patients (see Image 10); these represent nonuniform growth of the tumor rather than true septa. The tumors are typically in the range of 5-7 cm in diameter when they are discovered. Most giant cell tumors (85%) occur in the long bones; approximately 50% are located in the bones around the knee. Location is important in the diagnosis of giant cell tumor. Most tumors are eccentric and are seen in a subarticular location (see Image 11); however, the tumor originates in the metaphysis, and the common epiphyseal involvement is the result of the patient's skeletal maturity. Early lesions may lie solely in the metaphysis. A narrow zone of transition with a lack of sclerosis at its margins is a distinctive finding and strongly suggestive of the diagnosis. When sclerosis of the tumor margins is present, it is seldom complete. Periosteal reactions are not usually seen; the lack of a host-reactive response is typical of giant cell tumors. Giant cell tumors in the spine are uncommon and account for only 5% of giant cell tumors. The sacrum is the most common location. Patients with these tumors tend to be slightly younger than those with tumors in the appendicular skeleton. The location in the vertebrae can vary, but the tumor most commonly involves the vertebral body. On radiographs, the tumors may be seen in areas of destruction of the vertebral body with invasion of the posterior elements. The tumor can cause vertebral collapse and spinal cord compression, especially when it involves the posterior elements.Degree of ConfidenceThe degree of confidence is high for radiography in the appendicular skeleton. In the spine, the degree of diagnostic confidence is not high, as giant cell tumors usually cannot be differentiated from other types of tumors. Tumors in the sacrum are recognizable, and these may be diagnosed on the basis of their appearance and location. False Positives/NegativesUnusual forms of certain tumors may mimic giant cell tumors. Telangiectatic or fibrogenic variants of osteosarcoma may not produce visible ossifications or calcifications. These variants may be eccentric and may extend to the subarticular surface, mimicking a giant cell tumor. Malignant fibrous histiocytomas occur in a similar age group and can also mimic a giant cell tumor. Brown tumors of hyperparathyroidism are well known in the differential diagnosis of giant cell tumors. Chondroblastomas may be mistaken for giant cell tumors because of their subarticular location; however, careful review of the radiographs usually reveals that the epicenter lies in the epiphysis rather than in the metaphysis. The presence of chondroid calcifications further supports the diagnosis of chondroblastoma. Aneurysmal bone cysts may be only slightly expansile in the early stages, and they can extend to the subarticular cortex, mimicking a giant cell tumor. These cysts usually occur in younger patients. Approximately 29% of aneurysmal bone cysts are reported to be associated with some other solid bone lesion, 39% of which are giant cell tumors. CT SCANSection 5 of 10
FindingsCT findings are similar to radiographic findings (see Image 12) for giant cell tumor of bone. Marginal sclerosis, cortical destruction, and soft-tissue masses (see Image 13) are seen more clearly on CT scans than on radiographs. Fluid-fluid levels are occasionally seen but are not specific. Degree of ConfidenceThe degree of confidence is high when CT is used in conjunction with radiography. CT does not usually add much diagnostic information to the radiographic results. CT scans are more useful in complex-shaped bones, such as the vertebrae or pelvic bones, because the details of the lesion may not be depicted well on radiographs (see Images 14-16). CT is also useful in surgical planning. MRISection 6 of 10
FindingsOn T1-weighted images, giant cell tumors may show heterogeneous or homogeneous signal intensity characteristics. The signal intensity is usually low or intermediate, but areas of high signal-intensity, caused by recent hemorrhage, may be noted. On T2-weighted images, heterogeneous low-to-intermediate signal intensity is seen in solid areas of the tumor (see Image 17). Areas of low signal intensity may be exaggerated on T2-weighted spin-echo images, and these may be even more exaggerated on gradient-echo weighted images because of the presence of hemosiderin. Hemosiderin is detected in more than 63% of giant cell tumors, and its presence is probably the result of extravasated red blood cells coupled with the phagocytic function of the tumor cells. Cystic areas are common and are seen as areas of high signal intensity on T2-weighted images. Fluid-fluid levels may be seen (see Image 18). Peritumoral edema is uncommon in the absence of a fracture. The tumor is usually heterogeneously enhancing with the intravenous administration of contrast material. Degree of ConfidenceThe degree of confidence of MRI is high for imaging the appendicular skeleton. The MRI findings for giant cell tumors of the lower spine may overlap with those of other tumors, such as osteoblastoma, aneurysmal bone cyst, and metastasis. MRI is sensitive for the detection of soft-tissue changes, intra-articular extension, and marrow changes. MRI is the best method for assessing subchondral breakthrough and the extension of tumor into an adjacent joint. Its diagnostic accuracy is high, especially when MRIs are interpreted in conjunction with plain radiographs. False Positives/NegativesIn the spine, tumors such as osteoblastoma, aneurysmal bone cyst, and metastasis may be found in the same location as giant cell tumors, and they may have overlapping MRI characteristics. NUCLEAR MEDICINESection 7 of 10
FindingsUptake in giant cell tumors is usually diffuse in all phases. The degree of uptake is not correlated with the grade of the tumor or the malignancy. Bone scanning is not usually required in the evaluation of a giant cell tumor, except for the rare case in which multicentric giant cell tumors are suspected. Degree of ConfidenceThe degree of confidence is low with nuclear medicine studies. Giant cell tumors cannot be confidently differentiated from other tumors and diseases by using bone scans alone. False Positives/NegativesTracer uptake is not specific for giant cell tumors. ANGIOGRAPHYSection 8 of 10
FindingsAngiography is not usually required in the evaluation of a giant cell tumor. Neovascularity is demonstrated in 80% of giant cell tumors, along with an intense, inhomogeneous capillary blush. Unfortunately, overlap in the angiographic features of malignant bone tumors, benign tumors, and nonneoplastic lesions precludes the use of angiography in making the differential diagnosis. Although angiography can be used to assess the intraosseous and extraosseous extent of a tumor, which is useful in planning surgery, MRI has largely replaced angiography in surgical planning. Preoperative embolization may be performed as a surgical adjunct to diminish bleeding and facilitate resection in highly vascular tumors. Complete removal of a tumor’s extraosseous component is mandatory to prevent local recurrence (see Image 19), which may be difficult in a highly vascularized tumor. Surgery is usually performed soon after embolization, before collateral vessels form (see Image 20). The arterial supply to a tumor can also be embolized in patients who are not candidates for surgery. In these patients, the aim is palliative pain relief. Degree of ConfidenceAngiographic features are not diagnostic of giant cell tumor. MULTIMEDIASection 9 of 10
REFERENCESSection 10 of 10
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