Malignant Bone Tumors in Children

Malignant Bone TumorsA timely diagnosis of malignant bone tumors in children reduces the likelihood of metastasis that dramatically reduces survival rates.

Evaluation

Evaluate tumors by taking the history, performing a careful physical examination, and obtaining necessary laboratory and imaging studies.

History

Tumors usually present as a soft tissue mass, produce pain, or cause disability. How long a mass has been present is often difficult to determine from a history. Frequently, a large lesion, such as a slow-growing osteochondroma, is not noticed until shortly before the consultation. The family may incorrectly conclude that the tumor had grown quickly.

Pain is a more reliable indicator of the time of onset of a tumor. Inquire about the onset, progression, severity, and character of the pain. Night pain is common for both malignant tumors and some benign lesions. Malignant lesions produce pain that increases over a period of weeks. Night pain in the adolescent is especially worrisome and should be evaluated first with a conventional radiograph. An abrupt onset of pain is usually due to a pathologic fracture. Such fractures most commonly occur through bone cysts typically found in the humerus and femur.

Race is notable, as blacks seldom develop Ewing sarcoma.

Examination

The initial examination is usually performed for a mass or pain. Some lesions are usually multiple. Look for asymmetry, deformity, or swelling. Palpate for masses. If a mass is present, measure its size, assess for tenderness, and note any associated inflammation. Malignant tumors are typically firm, are nontender, and may produce signs of inflammation. Be aware that the history of pain is often intermittent, especially for Ewing sarcoma, and a misleading history of minor trauma is common.

Osteosarcoma

Osteosarcoma commonly occurs during the second decade of life and often occurs about the knee. Pain with activities and a palpable mass are often early findings. Sometimes the patient presents with a pathologic fracture. Radiographs may show the classic features of an osteogenic lesion. Lesions may be either an osteolytic or osteogenic lesion of metaphyseal bone. Bone scans are helpful in identifying other affected sites. The histology shows tumor cells with primitive bone matrix formation.

Variants Osteosarcoma has several types with prognostic significance.

Parosteal osteosarcoma These well-differentiated lesions develop on the surface of the bone, such as the posterior femoral metaphysis, with little or no medullary involvement. Manage by wide local resection.

Ewing Sarcoma

These tumors cause pain and sometimes present with a soft tissue mass. The lesion is diaphyseal and osteolytic or permeative in character. Bone scans and MRI are useful. Because the tumor may cause fever, leukocytosis, anemia, and an elevated sedimentation rate, it can be confused with osteomyelitis. Confirm the diagnosis by biopsy.

Management Management principles are similar for both osteosarcoma and Ewing sarcoma. In general, Ewing sarcoma is primarily managed by chemotherapy and resection and often adjunctive radiation therapy.

Chemotherapy Chemotherapeutic agents are used in regimens of 3 to 5 agents given over a period of about 9 to 12 months, Typically, a third is administered preoperatively for a period of 6 weeks and the rest following resection for an additional 6 to 9 months.

Operative options Make the choice based on a discussion with the patient and family. Outcomes for various procedures are often comparable, and the choice is often best made based on the features of the tumor. Limb-sparing procedures have the greatest appeal to the child and family and have become the standard of care for most patients.

Amputation versus limb-sparing procedures Each method has its indications and contraindications. Functional outcomes are about the same. Patients managed by amputation have slightly lower functional scores but experience fewer complications from the surgery.

Endoprosthesis Modular prosthetic management is gaining favor with time. Modern prostheses are strong, lightweight, and nonreactive. Rehabilitation can commence immediately, and acceptance is good. Infection and loosening are major problems. Problems with tendon and ligament attachments can occur. Replacements about the knee, especially the proximal tibia, are most problematic and demonstrate the highest failure rates. Between 30% and 40% require revisions within the first decade following replacement. Most infections and loosening problems can be resolved by revisions.

Expandable endoprosthesis For children, provide an option to maintain equal limb lengths. Design allows 6-9 cm with 1.5–2 cm expansion by minimally invasive procedures. Design improvements allow greater excursion and stable design.

Allografts Allografts may be intercalary, osteoarticular, or composites, combined with an endoprosthesis. Nonunion is the most common problem. The allografts never completely incorporate, but they stabilize with time. This provides improved long-term function, making this a good choice for young people with long-bone diaphyseal tumors. In addition, attachments of tendons and ligaments are more satisfactory than with endoprostheses. Although intercallary allografts have the best results, osteoarticular reconstructions may be considered, especially about the knee. Because of tendon-ligament attachment capability, use around the knee has advantages over endoprostheses. Allograft outcomes may be improved by tissue typing in the future.

Rotationplasty This option provides the most energy-efficient outcome, best suited for children under 10 years of age with extensive tumors. Complications are few, and outcome allows a prosthetic fitting that is durable and functional. Most children function in sports. The major drawback is the complexity of the reconstruction and the appearance of the reconstructed limb. Preoperative meetings with other patients who have had the procedure are recommended. Although not in vogue, some suggest the procedure is better suited for boys than girls.

Other alternatives These include vascularized grafts, bone transport for lengthening, and arthrodesis. These options are less commonly considered, but may have a role for specific needs.

The options of treatment are numerous, making it necessary to integrate management and tailor management to the unique features of each child.

Leukemia

About 20% of children with leukemia present with bone pain and may first be seen by an orthopedist or rheumatologist. Common findings include bone pain, joint pain and swelling, antalgic gait, mild lymphadenopathy and hepatosplenomegaly, and a moderate fever. Radiographic findings include metaphyseal bands, sclerosis, and a combination of sclerosis and lytic features. Usual laboratory findings include an elevated ESR, anemia and blast cells. Confirm the diagnosis with a bone marrow biopsy.

Metastatic Bone Tumors

The primary tumors are neuroblastoma followed by rhabdomyosarcoma. Vertebrae metastases are common in the lumbar spine, whereas thoracic and cervical involvements are less common. The primary site of tumors with spinal involvement are neuroblastoma and astrocytoma, depending on the patient’s age. Complications of spinal metastasis include paralysis, pathologic fractures, and kyphoscoliosis. Assess children with neuroblastoma and Ewing sarcoma for bony metastatic disease by CT, MRI, scintigraphy, or bone marrow biopsy. Extensive bony involvement is a relatively late finding.

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