Categories of bone tumors:

• Matrix producing tumors
• Chondrogenic — cartilage forming (includes osteochondroma, chondroma, chondroblastoma, chondromyxoid fibroma, chest wall hamartoma, chondrosarcoma)
• Osteogenic — bone forming (includes osteoid osteoma, osteoma, osteosarcoma)
• Non-matrix producing tumors (includes giant cell tumor, giant cell granuloma, aneurysmal bone cyst, simple bone cyst, primary vascular neoplasms, nonossifying fibroma, Langerhans cell histiocytosis, Rosai-Dorfman disease, fibrous spindle-cell tumor)
• Round cell tumors — includes Ewing’s sarcoma, lymphoma, plasmacytoma

• Benign: well circumscribed with thick, regular new bone formation; usually slower-growing, producing geographic bone destruction resulting in sclerotic rim.
• Malignant: poorly circumscribed, growth forms multiple layers of poorly organized periosteal new bone (eg, "onionskin" appearance of Ewing’s sarcoma); slow-growing lesions will have moth-eaten lucencies, while faster-growing lesions will have permeative destruction.

1.Epidemiology:

a. Ewing’s sarcoma composed approximately 1% of all pediatric tumors, and is the secondmost common primary malignant bone tumor in this population.

b.There are a reported 3 cases per 1 million Caucasians under age 21 years

c. Incidence of Ewing’s sarcoma is more common in boys than girls, and rarely presents before age 5 years.

2. Clinical features:

a. Patients will often complain of constitutional symptoms (fever, weight loss).

b.The affected extremity may have pain and/or swelling with mild to moderate erythema.

c. Often the signs/symptoms mimic "playground" trauma,

d. Ewing’s sarcoma can also present with a pathologic fracture in 10-15% of cases.

3. Laboratory findings

a. Patients will typically have elevated LDH and alkaline phosphatase. LDH can be used as a marker to detect response to therapy as well as for recurrence.

4. Pathology:

a. 85% of Ewing’s cases have translocation t(11;22)(q24;q12), which is a fusion between EWS and either ETS transcription factor FLI-1 (90-95%) or ERG (5-10%). The EWS-FLI-1 fusion is associated with a more favorable prognosis. Rarely, a p53 mutation is associated with Ewing’s sarcoma; when present, it carries a very poor prognosis.

5. Therapy:

a. The standard approach to treatment for Ewing’s sarcoma is wide surgical resection followed by adjuvant chemotherapy (agents include doxorubicin, actinomycin, dactinomycin, cyclophosphamide, vincristine). Adjuvant radiotherapy is controversial but has been shown to reduce local recurrence.

Osteosarcoma

1. Epidemiology:

a. Osteosarcoma composes approximately 2.4% of all childhood cancers, with 1000 new cases diagnosed in the US yearly.

b. Incidence peaks in the second decade, with a second, smaller peak in adulthood (after age 50).

2. Clinical features:

a. Pain is the most common presenting symptom. It is often a dull, aching pain that can be referred and can also occur at night. Any child with unilateral extremity pain at night should be more closely evaluated.

b. Constitutional symptoms are uncommon, but there may often be a history of minor trauma, such as a sprain or muscle strain. Pathological fractures are not an uncommon presentation.

c. Physical exam may reveal local tenderness, swelling or even deformity.

3. Pathology:

a. There are no specific genetic mutations or chromosomal alterations associated with osteosarcoma, although patients with hereditary retinoblastoma have 1000x increased incidence of osteosarcoma.

b. 70% of sporadic case demonstrate an altered Rb gene. Many rearrangements and multiplications of chromosome number have also been described; patients who have a "near-diploid" number of chromosomes have a more favorable prognosis.

4. Therapy:

a. Treatment consists of a combination of chemotherapy and surgery.

b. Limb-sparing surgery combined with preoperative chemotherapy has been shown to be as effective as amputation.

c. Chemotherapeutic agents include cisplatin, ifosfamide, and high-dose methotrexate with leucovorin rescue.

d. Patients who present with localized disease currently have 60-80% survival.

References

1. Arndt C, Crist W. Common Musculoskeletal Tumors of Childhood and Adolescence NEJM July 29. 1999;342:342