The Unknown Cases Texas Radiological Society 92nd Annual Scientific Meeting San Antonio, TX April 13

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The Unknown CasesTexas Radiological Society
92nd Annual Scientific MeetingSan Antonio, TX
April 1-3, 2005

• Justin Q. Ly, MD
• Douglas P. Beall, MD
• Ernesto Torres, MD
• Daniel H. Duffy
• Department of Radiology and Nuclear Medicine
• Wilford Hall Medical Center/SAUSHEC Radiology
• Oklahoma University Health Sciences Center
• Brooke Army Medical Center

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CASE 1

• Male in 20s presenting with medial thigh pain and
  mass sensation

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(No Transcript)
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Findings

• XR-short segment aggressive periosteal reaction
  to include Codmans triangle (medial distal
  femoral shaft)
• CT-radiographic findings confirmed, no
  involvement of the inner cortex or endosteal
  surface
• MRI-absence of marrow involvement nonspecific
  ill-defined associated soft tissue mass,
  aggressive periosteal reaction/Codmans triangle
  again seen

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Diagnosis?

• Periosteal Osteosarcoma

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DDX (broad based on XR findings/location)

• Trauma
• Avulsive injury (adductor longus insertion)
• Stress fx (location is not good)
• Early myositis ossificans
• Tumor
• Osteoid osteoma
• Osteosarcoma
• Infection
• In the right clinical setting

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Osteosarcoma

• Most common primary sarcoma of bone
• 2nd most common primary malignant tumor (MM 1)

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Primary Osteosarcoma Classification

• Intramedullary-high grade 75
• Juxtacortical 7-10
• Gnathic 6
• Low grade sclerosing 4-5
• Soft tissue 4
• Osteosarcomatous-multifocal 1-2
• Intracortical 0.2

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Juxtacortical Osteosarcoma

• Parosteal 65
• Periosteal 25
• High-grade surface 10
• Prognosis varies with grade and extent of
  involvement

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Murphey MD et al. Imaging of Periosteal
Osteosarcoma Radiologic-Pathologic Comparison.
Radiology. 2004233129-138.

• 40 cases
• Age range 10-37 years (avg age, 20 years)
• Distinctive imaging appearance
• Diaphyseal lesion involving femur or tibia
• Cortical thickening / extrinsically eroded
  (scalloped) by broad-based soft-tissue mass
  attached to cortex
• Periosteal reaction (perpendicular to long axis
  of bone) extends into mass
• Additional areas of mineralization are frequently
  seen on radiographs
• CT and MR imaging show these features and reveal
  extent
• CT and MR imaging reflect largely chondroid
  tissue seen pathologically, which shows low
  attenuation at CT and high T2 signal
• MR reveals foci of marrow replacement in region
  of tumor (most cases reactive)
• Medullary invasion rare and should only be
  suggested when marrow replacement is in
  continuity with surface soft-tissue component
• THIS distinction (reactive vs invasion) important
  for determining extent of tumor resection

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?
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Juxtacortical Osteosarcoma

• Surface
• Parosteal
• Occurs after skeletal maturity
• Outer layer periosteum
• Exophytic growth, lobulated osssified mass _at_ post
  femoral metaph
• Early lesions may have cleavage plane b/n
  cortex/tumor
• Periosteal elevation/new bone formation lacking
• Low-grade with very good prognosis (worse if
  medullary invasion)
• DDX MO, osteochondroma (Parosteal OSA has
  cartilage cap)

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Juxtacortical OSA

• High Grade Surface
• Least common surface type
• Similar in appearance to periosteal osa, mets
  more common/ worse prognosis

Mark MD, et al. Archives of the AFIP The Many
Faces of Osteosarcoma. RadioGraphics 199717 .
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Juxtacortical Lesions

• OSA
• Parosteal 65 (centrally calcified)
• Periosteal 25
• High-grade surface 10
• Myositis Ossificans (peripheral rim of
  calcification)