Osteosarcoma

By admin On Feb 17, 2024

Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.

Title: 5-Minute Orthopaedic Consult, 2nd Edition

> Table of Contents > Osteosarcoma

Osteosarcoma

Frank J. Frassica MD

Basics

Description

The most common primary malignant bone tumor in children and young adolescents
May occur occasionally in older adults but is much less common than chondrosarcoma and MFH
May occur within other lesions (secondary sarcoma) such as Paget disease, bone infarcts, and irradiated bone
A highly malignant tumor with invasive local growth and early pulmonary metastasis
- Bones most commonly affected include those that grow most rapidly (1):
  - Femur: 41.5%
  - Tibia: 16.5%
  - Humerus: 15%
Classification: The many different types of osteosarcoma often are classified by their location and degree of differentiation.
- High-grade intramedullary: Most common type
- Well-differentiated intramedullary: Very rare
- Surface osteosarcomas:
  - Parosteal osteosarcoma: Most common
    surface osteosarcoma; well differentiated; occurs most commonly on the
    distal femoral or proximal tibial metaphysis
  - Periosteal osteosarcoma: Intermediate grade, predominantly cartilage with bone formation
  - High-grade: Very rare
- Osteosarcoma of the jaw: Behaves in a less malignant fashion than high-grade intramedullary osteosarcoma
- Lesions usually are staged according to the Enneking staging system (2), most commonly:
  - Stage IIB: High-grade, soft-tissue extension (80–90%)
  - Stage III: Metastatic disease (~10–15%)
Synonym: Osteogenic sarcoma

Epidemiology

Adolescents in their 2nd decade are the most commonly affected group.
The median age range at presentation is 13–17 years (1).
Some authors report a slight male predominance (1.3:1) (1).

Incidence

Primary sarcomas of bone are rare, with only ~2,500 new cases per year in the United States (1).
Osteosarcoma is one of the most common primary bone sarcomas, representing up to 40% (1).

Risk Factors

Osteosarcomas may occur (rarely) in abnormal bone.
- After irradiation
- Paget disease
- Bone infarcts

Etiology

The cause of classic high-grade osteosarcoma is unknown.
A relationship between incidence and high rates of growth has been noted.
Osteosarcoma occasionally develops in
areas of pre-existing bone lesions such as Paget disease, fibrous
dysplasia, bone infarcts, or OI.
The retinoblastoma often is present.

Associated Conditions

Retinoblastoma (high incidence of osteosarcoma)

Diagnosis

Signs and Symptoms

Pain and swelling are the most consistent symptoms of osteosarcoma.
Onset usually is gradual and progressive.
Pain is aching and persistent.
Many patients report night pain, which awakens them.

Physical Exam

A soft-tissue mass often is palpable and tender.
The mass frequently is warm and may limit ROM of the adjacent joint.
Once diagnosed, patients:
- Usually undergo a staging workup, including chest CT, MRI of the lesion, and technetium bone scan
- Should undergo a staging biopsy

Tests

Lab

Alkaline phosphatase is elevated in many patients.
In patients with a high pretherapeutic
alkaline phosphatase level, serial measurements may be used to monitor
therapeutic response and tumor recurrence.
Serum lactate dehydrogenase also may be elevated.

Imaging

The location of osteosarcoma usually is the metaphysis of a long bone.
Lesions typically show features of bone destruction, bone formation, periosteal reaction, and a mineralized soft-tissue mass.
The classic radiographic appearance is that of a destructive lesion of bone that is itself forming bone.
Rapid cortical destruction and periosteal reaction at the proximal or distal margin may produce the classic “Codman triangle.”
- Alternatively, radial reactive trabeculation may produce a sunburst appearance.
Lesions rarely involve the joint.

Pathological Findings

Many subtypes of osteosarcoma have been identified.
- All osteosarcoma types have a malignant fibrous stroma forming bone as a least common denominator.
- Broad histologic subtypes are as follows:
  - Fibrogenic
  - Chondrogenic
  - Osteogenic

Differential Diagnosis

Infection
Ewing sarcoma
Giant cell tumor
Metastatic disease
EOG

P.303

Treatment

General Measures

Any patient with a destructive lesion of a long bone
that is forming bone should be referred immediately to an experienced
musculoskeletal oncologist.

Activity

Once the diagnosis has been made, activity should be restricted to prevent fracture, which could necessitate an amputation.
Patients with lower-extremity tumors are placed on crutches.

Special Therapy

Physical Therapy

Most patients with local extremity lesions begin gait training with crutches to prevent pathologic fracture.
In the upper extremity, function of the hand and elbow must be maintained.

Medication

Multiple chemotherapy regimens are being developed, refined, and evaluated (3).
Current regimens include 3–6 different cytotoxic agents given for 10–12 weeks preoperatively and 6 months postoperatively (see “Prognosis” section).

Surgery

Historically, treatment generally consisted of amputation.
Newer surgical techniques and chemotherapeutic regimens allow limb salvage in most cases.
Resected bone segments may be replaced by allografts or large-segment metal prostheses, depending on the situation.
Limb salvage surgery can be accomplished in up to 90% of patients (4).

Follow-up

Prognosis

Historically, patients with primary osteosarcoma had a 5-year survival rate of only 20–30% (1).
Newer chemotherapeutic regimens are effective in killing occult metastases.
- With preoperative and postoperative multiagent chemotherapy and wide resection, long-term disease-free survival is 60–70% (3).

Complications

Development of lung and bone metastases is the most feared complication.
- Metastasis may occur years after diagnosis and treatment, but most occur within the first 2 years.
Other complications secondary to limb salvage surgery are relatively common and include:
- Local recurrence in ~5–10% of patients, usually within 2 years (4)
- Pulmonary metastases in ~1/3 of patients, usually found within 3 years (1)
- Infection
- Pathologic fracture
- Loosening of prosthetic components
- Wound breakdown

Patient Monitoring

After definitive treatment, patients should be followed to detect recurrence or metastasis.
Patients are monitored closely for the first 2 years with CT scans of the chest every 3–4 months to detect pulmonary metastases.
Plain radiographs of the limb are performed to detect local recurrences.

References

1. Dorfman HD, Czerniak B. Osteosarcoma. In: Bone Tumors. St. Louis: Mosby, 1998:128–252.

2. Enneking WF, Spanier SS, Goodman MA. A system for the surgical staging of musculoskeletal sarcoma. Clin Orthop Relat Res 1980;153:106–120.

3. Gebhardt
MC, Hornicek FJ. Osteosarcoma. In: Menendez LR, ed. Orthopaedic
Knowledge Update: Musculoskeletal Tumors. Rosemont, IL: American
Academy of Orthopaedic Surgeons, 2002:175–186.

4. McCarthy
EF, Frassica FJ. Primary bone tumors. In: Pathology of Bone and Joint
Disorders: With Clinical and Radiographic Correlation. Philadelphia: WB
Saunders, 1998:195–275.

Miscellaneous

Codes

ICD9-CM

170.9 Osteogenic sarcoma

Patient Teaching

Patients who have been treated successfully must be alert for any new areas of bone pain that could herald a bone metastasis.

FAQ

Q: Do all children with osteosarcoma need chemotherapy?

A: Chemotherapy is essential to improve the prognosis from only 20–30% to 65–75% long-term disease-free survival.

Q: Does limb salvage increase the risk of systemic spread?

A: Several studies have shown that limb salvage surgery does not increase the risk of pulmonary or bone metastases.

Q: Are there poor prognostic findings?

A:
Yes, several: Pulmonary metastases at initial presentation, location in
the pelvis or spine, increased serum alkaline phosphatase or lactate
dehydrogenase, and (very importantly) a poor response to chemotherapy.

Q: What are the greatest risks of limb salvage surgery?

A: Local recurrence and deep infection. Both these complications often necessitate amputation.