| Presentation |
- Symptoms
- pain
- slowly progressive dull aching pain
- not relieved by NSAIDS
- may see neurologic symptoms with spine involvement
- Physical exam
- swelling
- muscle atrophy
- limp
|
| Imaging |
- Radiographs
- recommended views
- AP and lateral of symptomatic area
- findings
- lytic or mixed lytic-blastic lesion with radiolucent nidus > 2cm
 
- reactive sclerotic bone
- 66% cortically based, 33% medullary based
- often expansile with extension into soft tissues with rim of reactive bone
- 25% appear very aggressive and often mistaken for malignant lesion
- CT
- indications
- necessary to fully evaluate lesion
- Bone scan
- hot with intense focal uptake
|
| Studies |
- Histology
- similar to osteoid osteoma but with more giant cells
- distinct demarcation between nidus and reactive bone
- nidus of immature osteoid and osteoblasts with abundant cytoplasm and normal nuclei
- fibrovascular stroma that merges with normal trabeculae of bone
- rim of osteoblasts surrounds osteoid
- numerous mitotic figures, but not atypical
|
| Treatment |
- Nonoperative
- observation
- indications
- rarely, if ever, indicated as the lesion will continue to grow
- Operative
- curettage or marginal excision with bone grafting
- indications
- recurrence 10-20%
|
| Differentials |
- Differentiating from osteoid osteoma
- difference
- rare and locally aggressive but benign (not self limiting)
- over 40% occur in posterior elements of spine or sacrum
- dull pain unresponsive to NSAIDs
- larger
- similarities
- usually younger patients (< 30 years)
- 2:1 male to female ratio
- Radiographic differential includes
- osteosarcoma
- ABC
- osteomyelitis
- osteoid osteoma
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| Image Bank |
| |
Location |
Xray
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CT
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Bone scan
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MRI
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Histology
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| Case A |
prox. humerus |
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| Case B |
prox. femur |
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-
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| Case C |
prox. femur |
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-
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| Case D |
spine |
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| Case E |
calcaneus |
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