Updated: 10/6/2016

Parosteal Osteosarcoma

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https://upload.orthobullets.com/topic/8015/images/Case A - posterior femur - xray - Parsons_moved.png
https://upload.orthobullets.com/topic/8015/images/Case A - posterior femur - MRI- Parsons_moved.png
https://upload.orthobullets.com/topic/8015/images/Histology A_moved.png
https://upload.orthobullets.com/topic/8015/images/Case B - post femur - xray Ap - Parsons_moved.png
https://upload.orthobullets.com/topic/8015/images/Histology C_moved.jpg
https://upload.orthobullets.com/topic/8015/images/parosteal osteosarcoma histology.jpg
Introduction
  • low grade osteosarcoma
  • Epidemiology
    • demographics
      • more common in females, age 30-40
    • location
      • occurs on surface of metaphysis of long bones
      • most common sites include posterior distal femur, proximal tibia, and proximal humerus
        • 80% cases occur in the femur
      • marrow invasion occurs in 25% of cases
  • Prognosis
    • 95% long term survival when local control has been achieved
      • dedifferentiation of parosteal osteosarcoma is a poor prognostic factor
      • invasion into the medullary cavity does not affect long-term survival
Symptoms
  • Presentation
    • often presents as a painless mass
    • limited joint motion can also be a presenting complaint for characteristic large posterior distal femoral lesions
Imaging
  • Radiographs
    • heavily ossified, lobulated mass arising from cortex   
    • appears stuck onto cortex
  • CT chest
    • mandatory staging study 
    • used to evaluate for pulmonary metastasis
  • MRI 
    • mandatory and must include entire involved bone
    • helps determine soft tissue/marrow involvement and skip lesions
  • Bone scan
    • mandatory imaging study
    • always hot
Histology
  • Characteristic histology 
    • low grade lesion
    • regularly arranged normal osseous trabeculae  
    • most prominent histologic feature are the atypical spindle cells seen between regularly arranged osseous trabeculae 
    • some cellular atypia should be seen to make diagnosis
  • Histology can be mistaken for fibrous dysplasia
  • high rate of MDM2 amplification and ring chromosome
Treatment
  • Operative
    • wide local surgical excision 
      • indications
        • standard of care in most patients
      • technique
        • many consider geometric osteotomy of involved bone to decrease long term morbidity and retain native joint
      • chemotherapy
        • chemotherapy not indicated unless there is a high grade component
      • outcomes
        • often curative
Groups & Differentials
  • Fibrous dysplasia (similar on histology, but xrays are different)
  • Myositis Ossificans Traumatica (juxtaposed to bone)
  • Osteochondral exostosis (shares cortex with bone)
  • Developmental defect at insertion of adductor magnus q
 
Bone surface lesion (cortex)
     Similar Histology  
Treated with surgery alone (2)
 
Parosteal osteosarcoma
       
 
Periosteal osteosarcoma
           
Periosteal chondroma
         •  
Osteochonroma / MHE
         •  
Developmental defect
           
Myositis ossifican  •            
Chondrosarcoma          
 
Adamantinoma          
 
Chordoma          
• (controversial)
 
Fibrous Dysplasia
     
     
ASSUMPTIONS: (1) Older patient is > 40 yrs; (2) assuming no impending fracture

 

IBank
  Location
Xray
Xray
CT
B. scan
MRI
MRI
Histo
Case A distal femur
 
Case B distal femur
 
Case C prox. humerus
 

 

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Questions (7)
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(OBQ12.47) A 24-year-old male presents with increasing knee pain over the last 6 months. He reports that he sustained a non-contact twisting injury to the knee 7 months ago while playing softball. His knee range of motion is full and his knee is stable to varus and valgus at 0 and 30 degrees of knee flexion. There is a grade 1 Lachman examination. His dial test reveals 30 degrees of external rotation at 30 degrees of knee flexion. A radiograph is shown in Figure A. A biopsy is performed and is shown in Figure B. What is the most appropriate definitive management? Review Topic

QID: 4407
FIGURES:
1

Reassurance and observation in 6 months with repeat knee radiographs

7%

(290/4271)

2

Neoadjuvant external beam radiation, wide surgical resection, and adjuvant chemotherapy

6%

(251/4271)

3

Wide surgical resection

45%

(1926/4271)

4

Neoadjuvant chemotherapy, wide surgical resection, adjuvant chemotherapy

38%

(1629/4271)

5

Neoadjuvant chemotherapy, marginal surgical resection, adjuvant chemotherapy

3%

(136/4271)

ML 4

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

(OBQ11.88) A 21-year-old male presents with increasing shoulder pain for the past 6 months. Radiograph, CT scan, bone scan, MRI, and histology slide are shown in Figures A through E. What is the most appropriate diagnosis? Review Topic

QID: 3511
FIGURES:
1

Ewing's sarcoma

2%

(24/1487)

2

Periosteal osteosarcoma

27%

(406/1487)

3

Parosteal osteosarcoma

60%

(885/1487)

4

Osteochondroma

7%

(100/1487)

5

Myositis ossificans

5%

(68/1487)

ML 3

Select Answer to see Preferred Response

PREFERRED RESPONSE 3
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