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https://upload.medbullets.com/topic/120472/images/codman_triangle.jpg
https://upload.medbullets.com/topic/120472/images/codman_triangle12osteo..jpg
https://upload.medbullets.com/topic/120472/images/onionskin_radiopedia.jpg
https://upload.medbullets.com/topic/120472/images/ewing_sarcoma_histo.jpg
Snapshot
  • A 12-year-old boy presents to the pediatric emergency department with pain in his right lower extremity. He was recently playing in soccer, but he denies any trauma to the leg. Physical examination is notable for mild swelling in the right mid-tibia and tenderness to palpation. A radiograph of the leg demonstrate periosteal elevation and "onion skinning" concerning for malignancy.
Introduction
  • Overview
    • neoplastic disease of the bone that most often arises in the
      • long bones of the extremities
      • pelvic bones
  • Epidemiology
    • incidence
      • children and adolescents are most commonly affected
        • median age of diagnosis is 15 years of age
  • Pathophysiology
    • chromosomal translocation t(11;22) leads to the production of oncogenic fusion proteins (EWS-FLI1) that enhance cellular proliferation and malignant transformtion
  • Genetics
    • chromosomal translocation between Ewing sarcoma breakage region 1 (EWS) and erythroblast transformation-specific family transcription factors (FLI1), t(11;22)
      • leads to the production oncogenic fusion proteins
Symptoms
  • Symptom
    • constitutional symptoms (in 10-20% of cases)
      • fever
      • weight loss
      • fatigue
    • pain at the site of involvement
  • Physical exam
    • swelling and tenderness at the site of involvement
Imaging
  • Radiography
    • indication
      • inital imaging study 
    • findings
      • "onion skin pattern" of osteolytic lesions 
        • commonly affecting the diaphysis of the bone
          • can also involve the metaphysis
      • Codman triangle 
        • periosteal elevation
  • MRI
    • indication
      • to evaluate for the extent of disease
        • provides an image with higher definition than radiography
  • Radionuclide bone scan
    • indication
      • to survery the entire skeletion for the presence of metastasis 
Studies
  • Invasive studies
    • open or core needle biopsy
      • indication
        • confirms the diagnosis
          • perform histology and molecular testing
      • finding
        • histology
          • small, round, blue cells that are poorly differentiated 
            • neuroectodermal origin
            • scant cytoplasm
        • molecular testing
          • chromosomal translocation of 11;22
Differential
  • Osteosarcoma
    • differentiating factors
      • malignat osteoblasts
      • lesions are most often found in the metaphysis
        • typically has a rim of bone formation (uncommon in Ewing sarcoma)
Treatment
  • Medical
    • chemotherapy
      • indication
        • typically initial treatment option in most cases
    • radiation therapy
      • indication
        • may be used if surgical resection is not indicated
  • Operative
    • resection
      • indication
        • treatment option for local disease
Complications
  • Metastasis
    • other bone sites
    • bone marrow
    • lungs
 

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