II. Epidemiology
-
Incidence: One in 100,000 aged 10 to 19 years old
- Second most common Bone Cancer (Osteosarcoma is most common)
- Accounts for one third of U.S. Bone Cancer cases
- Race
- Rare in black children (contrast with Osteosarcoma)
- More common in white and asian patients
- Age
- Median onset age 15 years old
- Gender
- Slightly more common in males
III. Risk Factors
- Chromosome 11 and 22 translocation (95% of cases)
- Chromosome 21 and 22 translocation (5-10% of cases)
IV. Types: Ewing Sarcoma Family of Tumors
- Ewing Sarcoma of Bone and Soft Tissue
- Peripheral Primitive Neuroectodermal Tumor (PPNET)
- Askin Tumors (primary chest wall tumors)
- When large, may interfere with breathing
V. Pathophysiology
- Small round cell undifferentiated tumor
- Likely derives from primitive neuroectodermal and neural crest cells or possibly stem cells
- Grouped with other blue round cell tumors (based on histology)
- Associated with Chromosome translocation t(11,22)
- Primary tumor distribution
- Metastatic locations
- Lungs
- Other bones
VI. Symptoms
- Pain and swelling limits range of motion of joint
- Constitutional (Fever, Weight loss)
- May present as Pediatric Limp
VII. Imaging
- XRay (may be normal)
- Bone destruction (75% of cases)
- Soft tissue extension (64% of cases)
- Reactive bone formation (25%)
- Classic onion-skinning appearance (lamellated periosteal reaction) in 23% of cases
- Sunburst pattern (radiating calcification) in 20% of cases
- MRI of lesion
- Defines extent of tumor involvement
VIII. Differential Diagnosis
- Osteosarcoma
- Osteomyelitis
- Rhabdomyosarcoma (if soft tissue lesion)
- Primary Lymphoma involving bone
- Langerhans Cell Histiocytosis
- Metastatic Neuroblastoma
IX. Evaluation
- Biopsy by surgeon or CT-guided biopsy
- Imaging to identify metastases
- Chest CT
- Bone scan
- Bone Marrow Biopsy
X. Management
- Surgical Excision with clear margin excision
- Chemotherapy (neoadjuvant before surgery and adjuvant after surgery)
-
Radiation Therapy Indications (contrast with Osteosarcoma, in which radiation is not used)
- Lung metastases
- Palliative Care
- Paraspinal tumors with neurologic compromise
- Positive margins on resection
- Unresectable tumor
XI. Prognosis
- Small, distal, localized tumors: 75% cure
- See Osteosarcoma for positive and negative prognostic factors
- Osteosarcoma share the same prognostic factors
- Pelvic tumors are also associated with worse prognosis
XII. Follow-up: Careful and long-term observation
- Relapse may occur even a decade after diagnosis
- Cardiotoxicity due to Chemotherapy (Anthracycline)
- Secondary malignancy (e.g. Osteosarcoma)
- Especially if radiation used