Approach Considerations
Because of its potential for metastasis and local, infiltrative destruction, the presence of a low-grade central osteosarcoma is an indication for treatment. The only contraindication for the treatment of osteosarcoma is the presence of widespread metastases. Palliative treatment may then be indicated.
The most important factor in the adequate treatment of low-grade central osteosarcoma is accurate diagnosis. Because of variability in the radiographic and histologic appearance of this lesion, the participation of a team consisting of a radiologist, pathologist, and orthopedic surgeon, all specializing in musculoskeletal oncology, is important. With accurate, prompt diagnosis and adequate surgical treatment, a low-grade central osteosarcoma is a curable lesion with a favorable prognosis.
Medical Therapy
The use of radiation therapy or chemotherapy in the treatment of low-grade central osteosarcoma is controversial because neither has been proven to be beneficial. [27]
Surgical Therapy
Wide excision, which may include amputation, is the treatment of choice for low-grade central osteosarcoma. [28, 9, 29] The disease's recurrence rate after such treatment is negligible, whereas the recurrence rate following curettage or marginal excision is 80-100%. Of the tumors that recur, 15% are high-grade lesions.
Surgical planning is based on the size and location of the lesion. With low-grade central osteosarcomas located in the extremities, the primary decision is whether limb salvage is possible or if amputation is necessary. [30, 31] The decision is based on the tumor's proximity to major neurovascular bundles or its invasion of them, as well as on whether it will be possible to adequately perform a wide excision without sacrificing two or more major compartments.
Intraoperatively, the gross appearance of a low-grade central osteosarcoma is that of dense fibrous tissue with variable amounts of bone. Enneking reported that tetracycline labeling may be useful in distinguishing the transition from healthy bone to tumor if this change is not visibly evident. [17]
Postoperative Care
The most important factor that affects the morbidity and mortality of low-grade central osteosarcoma is determination of whether the margins of the surgical specimen are free of tumor on histologic examination.
Complications
Surgical complications vary, depending on the location of the tumor and the surrounding structures. The most frequent complications include the following:
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Infection - If this complication develops at the site of a prosthesis used for limb salvage, eradication of the infection frequently requires removal of the prosthesis, and amputation is sometimes required
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Hematoma - This may cause failure of a locally rotated tissue flap
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Loosening of the endoprosthesis
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Distant metastases
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Local recurrence
Long-Term Monitoring
Monitoring for signs of a developing infection is vitally important. Prevention or early evacuation of hematomas is helpful in preserving locally rotated tissue flaps. Finally, attention should be turned to proper rehabilitation, which includes retraining of the patient so that functional use of an extremity can be restored after involved muscle groups have been resected.
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Standard radiographs of a low-grade central osteosarcoma of the distal femur.
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Magnetic resonance image (MRI) of low-grade central osteosarcoma of the distal femur.
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Magnetic resonance image (MRI) of low-grade central osteosarcoma of the distal femur.
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Magnetic resonance image (MRI) of low-grade central osteosarcoma of the distal femur.
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Bone scan of a low-grade central osteosarcoma of the distal femur.
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Photomicrograph of a low-grade central osteosarcoma (original magnification, X40). Courtesy of Dr Ronald Burns, Palmetto Richland Department of Pathology.
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Photomicrograph of a low-grade central osteosarcoma (original magnification, X100). Courtesy of Dr Ronald Burns, Palmetto Richland Department of Pathology.
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Photomicrograph of a low-grade central osteosarcoma (original magnification, X400). Courtesy of Dr Ronald Burns, Palmetto Richland Department of Pathology.
