Discussion: 
- a common benign but locally aggressive lesion of unknown etiology; 
- occurs chiefly in men between 20-50 yrs (after epiphyseal closure);
- tumor is expansile lytic lesion that involves the epiphysis & metaphysis;
- tumor may enlarge to occupy most of epiphysis & adjacent metaphysis;
- tumor may erode & penetrate subchondral bone, articular cartilage, & cruciate ligaments;
- location:
- epiphysis of distal femur, proximal tibia, & distal radius;
- other sites: fibula, sacrum, proximal humerus, & distal tibia;
- can occur in bones of pelvis, particularly ilium near SI joint and sacrum;
- spine:
- usually located in vertebral body;
- radiolucent lesion in vertebral body of a young patient is likely to be GCT; - staging:
- stage I:
- benign latent giant cell tumors;
- no local agressive activity;
- stage II:
- benign active GCT;
- imaging studies demonstrate alteration of the cortical bone structure;
- stage III:
- locally aggressive tumors;
- imaging studies demonstrate a lytic lesion surrounding medullary and cortical bone;
- there may be indication of tumor penetration through the cortex into the soft tissues;
- prognosis:
- tumors w/ malignant stroma tend to behave in malignant fashion;
- lesions that appear benign may metastasize;
- 5% of pts will have pulmonary metastases (2% risk of benign pulmonary metastasis in all cases and 6% risk in recurrent cases);
- tumor is considered benign if pulmonary lesions are histologically benign;
- pulmonary lesions may be cured w/ surgical resection;
- GCT involving the distal radius may be more aggressive than in other locations;
- differential dx:
- non ossifying fibroma;
- aneurysmal bone cyst;
- histoplasma
- Histoplasma Osteomyelitis Simulating Giant-Cell Tumor of the Distal Part of the Radius: A Case Report.
- hyperparathyroidism:
- may produce brown tumors that are radiographically & histologically similar to giant cell tumor of bone, w/ the exception
that brown tumors tend to be diaphyseal in location;
- unlike brown tumors, serum Ca is normal in GCT;
- Clinical Manifestations:
- pts report deep, persistent intraosseous pain that mimics an internal derangement of the knee.
- pathologic frx or reactive knee effusioin is initial symptom in about 1/3 of pts;
- Radiographic Features:
- well-defined lytic lesion that involves the metaphysis and epiphysis (typical of a giant cell tumor);
- CT Scan:
- helps determine is extact amount of cortical destruction and helps determine the optimal location of the cortical window;
- Bone Scans:
- bone scans may show decreased radioisotope uptake in the center of lesion (doughnut sign); (also found w/ ABC);
- MRI:
- help determine determine extent of tumor destruction;
- may be indicated when the tumor has eroded thru the cortex and allows determination of whether concomitant neurovascular
structures are involved;
- may help evaluate subchondral penetration;
- Histologic Studies;
- Treatment:
- due to proximity to articlar cartilage, excision of GCT of bone is difficult;
- because intralesional excision of GCT tends to leave tumor cells behind, past attempts of excision had been asociatted w/ high
recurrance rate (40%);
- GCT involving the distal radius may be more agressive that GCT in other locations;
- prior pathologic fracture should be allowed to heal before surgery is attempted;
- ref: Giant Cell Tumor With Pathologic Fracture: Should We Curette or Resect?
- Stage 1 or 2 Lesions:
- intra-lesional excision is treatment of choice;
- excision is facilitated by making a large cortical window;
- window must be large enough to allow complete access to every corner of the intra-osseous lesion;
- high speed burr is used to complete the excision, with care taken to remove 5 mm of normal bone surrounding the lesion;
- at completion of procedure (which usually involves placement of cement or bone graft in the cavity), window is replaced w/
bone graft or w/ bone graft substitute;
- note that in areas such as the distal ulna or fibula, en bloc excision is preferred over currettage because there is minimal functional
consequences of en bloc exision;
- motorized burr and cautery are used to complete and excision the excision;
- when motorized burr is used to debride the subchondral bone, the joint cartilage should be irrigated w/ chilled saline;
- Blackley, et al (1999), the authors followed 59 patients who underwent curettage and bone grafting of GCT lesions;
- 12% had a local recurrence (and all but one of these patients responded to revision currettage and/or soft tissue resection);
- low recurrence rate was due to meticulous debridement of GCT tissue which included use of a high speed burr;
- ref: Treatment of giant-cell tumors of long bones with curettage and bone-grafting.
- adjunctive measures:
- use of phenol, polymethacrylate, and liquid nitrogen;
- phenol can be extremely toxic, and if used at all, its concentration should be limited to 5%;
- these work by increasing the zone of necrosis at periphery of excision;
- cement:
- heat generated from the polymerization reaction may kill tumor cells 0.5 mm in cortical bone and 2 mm in cancellous bone;
- as reported by O'Donnell, et al (1994) the use of cement did not appear to improve the results as compared to historic
controls with a 25% recurrence rate w/ long term follow up;
- barium impregnated cement allows for accurant determination of local recurrance;
- cement provides mechanical support following curretage and does not appear to affect cartilage when placed in the
subchondral region;
- when cement is applied beneath subchondral cartilage, joint should be irrigatted w/ chilled saline, inorder
to protect cartilage;
- Recurrence of giant-cell tumors of the long bones after curettage and packing with cement.
- liquid nitrogren:
- may cause excessive tissue necrosis, extending into normal tissue;
- bone grafting:
- Supplemental Bone Grafting in Giant Cell Tumor of the Extremity Reduces Nononcologic Complications.
- Recurrent or Stage 3 Lesions:
- this category includes frx w/ major pathologic frx, articular or cortical penetration by the tumor;
- en bloc excision w/ wide margin along w/ appropriate reconstruction;
- en bloc excision involves removal of one side the joint, necessitating a major limb reconstructive procedure (often w/ allografts);
- chemotherapy:
- Denosumab, a Potential Alternative to the Surgical Treatment of Distal Radius Giant Cell Tumor of Bone: Case Report
- radiation therapy
- traditionally XRT is avoided because of the possibility of malignant degeneration of the tumor;
- in the report by Chakravarti, et al JBJS 1999, 20 patients underwent a single course of megavoltage radiation (40-70 gray
administered at 1.8 to 2.0 gray per fraction with an average total duration of treatment of 5-7 weeks)
- after a median duration of follow-up of 9.3 years, the tumor had not progressed in seventeen of the twenty patients;
- no radiation-induced tumors were observed in our series;
- authors note that the results of XRT were comparable to published efficacy of surgical resection;
- references:
- Megavoltage Radiation Therapy for Axial and Inoperable Giant-Cell Tumor of Bone.
- pulmonary metastasis:
- 5% of pts will have pulmonary metastases;
- tumor is considered benign if pulmonary lesions are histologically benign;
- pulmonary lesions may be cured w/ surgical resection;
- references:
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