Case Report

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Radiological Category
Principal Modality (1) Principal Modality (2)
Musculoskeletal
General Radiography
CT/MRI
Case Report
Submitted by
Robbie Honey
Date accepted
30 August 2007
Faculty Reviewer Sandra A. A. Oldham, MD
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Case History

• 16 year-old African American male who presents
  with 3 weeks of pain and swelling in his left
  thigh. Pain is gradually getting worse (greatest
  amount 5/10) as well as the swelling. The pain
  is worse with activity and bending the leg.
  There is no history of trauma or fall. Parents
  have also noticed the patient has begun to limp.
  Patient has taken pain medication only once.

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Radiological Presentations

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Radiological Presentations

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Radiological Presentations

Non-contrast CT
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Radiological Presentations

T1 Post Contrast
T2
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Test Your Diagnosis
Which one of the following is your choice for the
appropriate diagnosis? After your selection, go
to next page.

• Conventional osteosarcoma
• Parosteal osteosarcoma
• High grade surface osteosarcoma
• Dedifferentiated parosteal osteosarcoma
• Osteochondroma
• Periosteal osteosarcoma

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The conventional radiograph shows an extensive
osseous tumor involving the diaphysis of the left
femur with a cumulus cloud appearance. There
is a marked sunburst type periosteal reaction
that is prominent on the medial aspect of the
femur. The tumor appears largely cortically
based with extension into the surrounding soft
tissues and likely medullary involvement. No
pathological fractures. CT shows that the lesion
is predominantly on the surface of the femur. In
addition there is extension into the soft tissue
with a large central component that is not
mineralized. MRI shows similar findings to CT
with areas of low signal on T1 corresponding to
dense mineralization as well as a large soft
tissue mass with an area of non-enhancement
likely representing necrosis. In addition,
within the medullary cavity there is diminished
T1 signal intensity and increased T2 signal
intensity representing either peritumoral edema
or infiltrative extension of the tumor.
Findings and Differentials
Findings
Differentials

• Parosteal osteosarcoma
• High-grade surface osteosarcoma
• Periosteal osteosarcoma
• Dedifferentiated parosteal osteosarcoma

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OS survival
Parosteal OS 4 gt 90 Dedifferentiated
POS 1 lt 10 Periosteal OS 1 gt 80 High-grade
surface OS 1 lt 10
J A
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Discussion

• Parosteal osteosarcoma is the most common surface
  osteosarcoma, typically affecting patients in the
  second to fifth decades of life and women more
  commonly. They typically occur in the long
  tubular bones, with the femur being the
  predominant site. Parosteal osteosarcomas are
  particularly common on the posterior surface of
  the distal portion of the femur and typically
  arise in a metaphyseal location.
• The radiographic abnormalities are highly
  characteristic. A large, radiodense, oval, or
  spheroid mass possessing lobulated or irregular
  margins is evident. Typically, it is attached in
  a sessile fashion to the external cortex. A thin
  radiolucent line, or cleavage plane, may separate
  the remaining portion of the tumor from the
  underlying bone. Overall the tumors tend to have
  a mushroom-like configuration. Involvement of
  the medullary cavity is minimal.
• Grossly the tumors are rock-hard, ivory white,
  and well defined with a sharp interface between
  the tumor and overlying soft tissues.
• Histologically these are generally regarded as
  low-grade osteosarcoma.
• Treatment is complete surgical extirpation, with
  local recurrence of 100 if incomplete removal.

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Discussion

• Dedifferentiated parosteal osteosarcoma
  represents a tumor in which there is association
  between conventional parosteal osteosarcoma and
  high-grade sarcoma (osteo, fibro, or malignant
  fibrous histiocytoma) and can occur either
  primarily or secondarily. Most common from 3rd
  to 5th decades and women greater then men. Most
  commonly the posterior distal femur is involved.
• Radiographically, appears very similar to
  conventional parosteal osteosarcoma. However
  frequently there are areas of lucency that may
  correspond to areas of high grade tumor within
  low grade tumor. In addition, arteriograms often
  show localized hypervascularity that tends to
  correspond to areas of high grade sarcoma.

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Discussion
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Discussion

• Periosteal osteosarcoma is an infrequent neoplasm
  that predominates in the second and third decades
  of life. Involvement of the diaphysis of a long
  tubular bone, especially the femur or tibia, is
  typical.
• Periosteal osteosarcomas are variable in size and
  on radiographs appear as lesions on the bone
  surface. The tumor is limited to the cortex,
  which is thickened and irregular externally this
  feature is commonly accompanied by
  nonhomogeneous, radiating osseous spicules that
  extend from the superficial region of the cortex
  into the adjacent soft tissues and are linear and
  perpedicular to the long axis of the parent bone.
  Attachment tends to be broad based. It should
  be emphasized that the medullary cavity, with
  rare exception, is uninvolved.
• Histologically, periosteal osteosarcoma is a form
  of relatively low to intermediate grade
  chondroblastic osteosarcoma arising from the bone
  surface.

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Discussion

• High-grade surface osteosarcoma is the least
  common of all the forms of osteosarcoma. It
  occurs most often in the second and third
  decades. Men are more commonly affected (41).
  The femur is the most common location.
• There are no radiographic features that are
  specific to HGS. It may appear as a radiolucent
  mass with minimal intralesional calcification on
  the surface of the involved bone and thus mimic
  periosteal osteosarcoma. Alternatively, it may
  form a radiopaque sunburst lesion confined to
  the periosteal surface and overlying soft
  tissues.
• Grossly, HGS is not rock-hard, well defined,
  bosselated, and ivory white such as conventional
  perosteal osteosarcoma. Primary dedifferentiated
  OS also has these features. Additionally HGS
  does not have the appearance of well-formed,
  grayish blue hyaline cartilage such as periosteal
  OS.
• Histologically, the hallmark of HGS is the
  presence of pure, high-grade sarcoma.

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Discussion

• The gold standard in imaging diagnosis of
  osteosarcoma remains the conventional
• radiograph. CT, MRI, and radionuclide
  examination are more useful for defining
• the extent of the neoplasm, including metastases,
  and its relationship to
• surrounding neurovascular structures. On MRI the
  neoplasm is typically of low
• signal intensity on T1-weighted spin echo, high
  intensity on T2 weighted images,
• and enhances with IV gadolinium.
• The distinction between dedifferentiated
  parosteal OS and high grade surface OS
• requires the use of histology and gross
  correlation.
• The distinction between high grade neoplasms
  (parosteal OS / HGS) and low grade
• neoplasms is important because of the indication
  for chemotherapy in high grade
• lesions.

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Osteosarcoma, osteoblastic, high grade
(High-grade surface osteosarcoma vs.
dediffentiated parosteal osteosarcoma)
Diagnosis
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Miller, Mark D. Review of Orthopaedics. 4th
ed. Saunders, 2004. 264-265.Raymond, Kevin A.
Surface Osteosarcoma. In Clinical
Orthopaedics. Vol. 270. September, 1991. 140
148.Resnick, Donald. Krandorf, Mark J. Tumor
and Tumor-Like Lesions of Bone Imaging and
Pathology of Specific Lesions. In Bone and
Joint Imaging. 3rd Edition. Elsevier Saunders,
2005. 1131-1139.Wang, Lisa L. Chintagumpala,
Murali. Gebhardt, Mark C. Osteosarcoma
Epidemiology, pathogenesis, clinical
presentation, diagnosis, and histology.
www.uptodate.com. Chart, pathology, and
radiographic example slides adapted with the
permission of A. Kevin Raymond, M.D., M.D.
Anderson Cancer Center
References