What Is Telangiectatic Osteosarcoma?
Osteosarcoma generally refers to cancer that develops on bone cells. It mainly affects the bones in the legs, arms, and thighs. Telangiectatic osteosarcoma is a rare subtype of high-grade malignant osteosarcoma that constitutes less than four percent of all osteosarcoma cases. The word telangiectatic refers to the condition pertaining to telangiectasis (the process of abnormal dilation of capillaries and small blood vessels). The lesions usually comprise large cystic cavities containing necrotic elements and hemorrhage (bleeding). It tends to recur often with increased susceptibility to pathologic fracture. It most commonly affects people between the ages of 3 and 71, with a median age of 20. Males are most commonly affected than females, with a ratio of 2:1. The most common sites of telangiectatic osteosarcoma include the metaphysis of long bones such as:
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Distal femur.
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Proximal tibia.
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Proximal humerus.
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Pelvis (hip bone).
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Skull bones.
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Ribs.
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Mandible (lower jaw bone).
The lesions of telangiectatic osteosarcoma are generally osseous (within the bone), but a few cases of extraosseous telangiectatic osteosarcoma are reported in the literature.
What Causes Telangiectatic Osteosarcoma?
The exact cause and factors predisposing to the formation of telangiectatic osteosarcoma are still unknown. However, some reports suggest that the development of telangiectatic osteosarcoma is associated with mutations of specific genes such as;
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Tumor Suppressor Genes - Such as Rb-1 (retinoblastoma gene 1) and p53 (tumor protein 53).
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Oncogenes - Such as HER2 (human epidermal growth factor receptor 2) and c-fos (proto-oncogene) gene.
Prior radiation exposure is considered a risk factor for developing telangiectatic osteosarcoma. Telangiectatic osteosarcomas can potentially develop in bones that are priorly affected by Paget's disease.
What Are the Symptoms of Telangiectatic Osteosarcoma?
The symptoms of telangiectatic osteosarcoma are mostly similar to conventional osteosarcoma and aneurysmal bone cyst. The most common symptoms of telangiectatic osteosarcoma include:
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Localized, dull bone pain.
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Swelling and tenderness around the affected bone.
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Worsening of pain at night.
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Soft tissue swelling.
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Restricted movement of the affected joint.
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Increased chances of pathologic fracture (a bone fracture caused by disease rather than an injury) of the affected bone.
How Is Telangiectatic Osteosarcoma Diagnosed?
Doctors primarily do a physical examination to look for the symptoms of telangiectatic osteosarcoma. In addition, the doctor might undertake a detailed medical history of the patient to check for any prior radiation exposure.
The doctor will recommend further diagnostic tests to differentiate telangiectatic osteosarcoma from other bone disorders. It includes:
A) Imaging Tests:
The following are the different imaging tests that help in the diagnosis of telangiectatic osteosarcoma:
1. X-ray: The radiographic features of telangiectatic osteosarcoma depicted through X-ray include:
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A poorly marginated osteolytic lesion with indistinct borders.
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The lesion often tends to expand, disrupting the cortical bone with no periosteal bone (new bone formed in response to injury).
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Bone sclerosis (an increase in bone density and hardening of bone) is absent.
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Expansion of contour of the affected bone.
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Pathologic fracture is visualized.
2. MRI (Magnetic Resonance Imaging): Unlike X-rays, MRI uses a powerful magnetic field to produce detailed images of the body. It helps in determining the extent of the tumor and soft tissue mass.
3. Bone Scan: A bone scan is an imaging test in which a radioactive material (radioactive tracer) is injected into the bloodstream that helps differentiate healthy and affected bone. As a result, the radioactive tracer gets deposited more on the areas of bone that are either breaking down or undergoing repair. The radioactive tracer deposited on the bones is detected through a scanner that helps diagnose bone fractures, infections, or other problems.
Bone scan for telangiectatic osteosarcoma reveals increased radioactive tracer uptake by the lesion.
B) Biopsy:
The doctor recommends a biopsy test for a definitive diagnosis of telangiectatic osteosarcoma. In a biopsy, a small amount of tissue is removed from the affected area and sent to the laboratory for pathological examination. In addition, a biopsy test helps differentiate telangiectatic osteosarcoma from other bone conditions, such as aneurysmal bone cysts and conventional osteosarcoma.
What Are the Diagnostic Criteria for Telangiectatic Osteosarcoma?
The diagnostic criteria for telangiectatic osteosarcoma include the following;
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Radiographically it resembles a destructive osteolytic tumor with no mineralization or periosteal bone formation.
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Histologically, it resembles a tumor with solitary or multiple cystic cavities filled with blood or necrotic tissue. The tumor consists of thin septa, which contain anaplastic tumor cells (cancer cells that proliferate rapidly and are different from normal cells).
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Pathologically, it exhibits a variable gross appearance with no dense bone areas and little solid tumor tissue.
How Is Telangiectatic Osteosarcoma Treated?
The treatment for telangiectatic osteosarcoma mainly involves surgical therapy and chemotherapy.
Surgical Therapy: The surgical treatment for telangiectatic osteosarcoma depends on the following:
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Tumor's location.
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Stage of the disease.
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Tumor's response to neoadjuvant chemotherapy (chemotherapy given before surgery).
Wide surgical resection of tumors and neoadjuvant chemotherapy are ideal for treating non-metastatic lesions. However, in the case of metastatic telangiectatic osteosarcoma, limb-sparing surgery is done. In limb-sparing surgery, the tumor is surgically removed from the limb without removing the whole limb.
Chemotherapy:
Chemotherapy means killing cancer cells with drugs. For the treatment of telangiectatic osteosarcoma, neoadjuvant and adjuvant chemotherapy (chemotherapy given after surgery) is provided.
For both neoadjuvant and adjuvant chemotherapy, two to six cycles of the following chemo drugs are administered either intravenously (IV) or intra-arterially:
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Doxorubicin.
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Methotrexate.
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Cisplatin.
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Ifosfamide.
What Are the Differential Diagnosis of Telangiectatic Osteosarcoma?
The differential diagnosis of telangiectatic osteosarcoma includes:
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Conventional Osteosarcoma: Osteosarcoma is a malignant bone tumor most commonly occurring in children. Conventional osteosarcoma is similar to the clinical presentation of telangiectatic osteosarcoma, but telangiectatic osteosarcoma shows a better response to chemotherapy than osteosarcoma.
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Aneurysmal Bone Cyst: An aneurysmal bone cyst is a benign bone tumor composed of multiple spaces inside the cyst filled with blood. Telangiectatic osteosarcoma is often misdiagnosed as an aneurysmal bone cyst since both exhibit several similar clinical and radiographic features.
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Fibrosarcoma: Fibrosarcoma is a rare malignant tumor derived from fibrous connective tissue. It differs from telangiectatic osteosarcoma histologically as it exhibits spindle-shaped cells arranged in a herringbone pattern (cells arranged in parallel lines which interact in a zig-zag pattern).
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Brodie's Abscess: Brodie's abscess is atypical osteomyelitis usually seen in the metaphysis of long bones. It is characterized by acute or chronic infection of the affected bone with the development of a localized abscess.
Conclusion
Telangiectatic osteosarcoma often responds better to chemotherapy than conventional osteosarcoma. The survival rate of telangiectatic osteosarcoma with current chemotherapy protocols is 65 percent after five years. In addition, neoadjuvant chemotherapy helps prevent the tumor's local recurrence post-surgical treatment.
