Osteogenic sarcoma is treated by radical excision and adjuvant chemotherapy. Before one proceeds for treatment, the clinical and radiographic diagnosis should always be confirmed by histologic examination of adequate tissue obtained by open biopsy.
Exuberant callus of a stress fracture, subacute osteomyelitis, active myositis ossificans, aneurysmal bone cyst, and eosinophilic granuloma are some of the benign conditions that can easily be mistaken for osteogenic sarcoma. Ewing’s sarcoma, fibrosarcoma, and metatastic carcinoma are some of the malignant lesions that must be considered in the differential diagnosis.
Staging
Staging of the lesion should precede open biopsy.
The objectives of staging are
- To establish the final tissue diagnosis
- To define the local extent of the tumor
- Discover any distant metastasis.
Both staging and open biopsy should be carried out by the surgeon who will perform the definitive operation.
In preoperative staging of osteogenic sarcoma the following diagnostic tests are performed:
- Complete history and physical examination
- Complete blood count with differential, erythrocyte sedimentation rate, and serum levels of calcium, phosphates, and alkaline phosphatase.
- Conventional radiograph of the part and the chest
- Scintigraphy with technetium-99m and in selected cases also with gallium-67 citrate
- Linear tomography to assess longitudinal intraosseous extent.
- Computed tomography of the part involved by the primary tumor and of the chest (to rule out metastases).
- Nuclear magnetic resonance imaging and
- Biplanar peripheral angiography in selected cases, especially if limb salvage is contemplated.
If the staging, open biopsy, and histologic examination of frozen sections indicate the tumor is osteogenic sarcoma, the pediatric oncologist (who is also a hematologist) should perform a bone marrow examination when the patient is under general anesthesia.
Biopsy
It is crucial to verify the site of biopsy by radiograph in the operating room. To ascertain that you have taken the diagnostic tissue, you must obtain frozen sections.Moreover cultures of the tissue specimen should be taken.
Dangers of Biopsy
There is always danger of the tumor spreading as a result of open biopsy. To prevent spilling neoplastic cells into vascular channels it is advisable to use a coagulation diathermy knife at biopsy. Proponents of immediate ablation argue that biopsy delays radical therapy.
An experienced pathologist might make a correct diagnosis on the basis of a frozen section but it is always best to rely on permanent sections for final diagnosis.
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