Updated: 11/2/2020


Review Topic
3 3
https://upload.orthobullets.com/topic/8013/images/Case B - xray - Parsons_moved.png
https://upload.orthobullets.com/topic/8013/images/Case B - CT - Parsons_moved.png
https://upload.orthobullets.com/topic/8013/images/Histology C - parsons_moved.png
https://upload.orthobullets.com/topic/8013/images/Case B - bone scan - Parsons_moved.png
https://upload.orthobullets.com/topic/8013/images/Case C - xray - Parsons_moved.png
https://upload.orthobullets.com/topic/8013/images/osteoblastoma ct.jpg
  • Aggressive benign osteoblastic tumor of bone 
    • "big brother" of osteoid osteoma (nidus > 2cm)
  • Epidemiology
    • incidence
      • relatively rare
      • less common than osteoid osteoma
    • demographics
      • males > females (2:1)
      • majority of patients 10-30 years of age
    • location
      • most common in posterior elements of spine
  • Genetics
    • unknown
  • Associated conditions
    • oncogenic osteomalacia
    • secondary ABC
      • 10%-40% associated with secondary ABC
  • Symptoms
    • pain
      • slowly progressive dull aching pain
      • not relieved by NSAIDS
    • may see neurologic symptoms with spine involvement
  • Physical exam
    • swelling
    • muscle atrophy
    • limp
  • 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 
  • 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
  • Radiographic differential for osteoblastoma includes
    • osteosarcoma
    • ABC
    • osteomyelitis
    • osteoid osteoma
  • Differentiating from osteoid osteoma
    • characteristics specific to osteoblastoma
      • rare and locally aggressive but benign (not self limiting)
      • over 40% occur in posterior elements of spine or sacrum 
      • dull pain less likely to be relieved by NSAIDs 
      • larger
      • more giant cells
  • Differential for lesions of the posterior spinal elements elements includes
    • aneurysmal bone cyst
    • osteod osteoma (see table below)
    • osteoblastoma

Osteoid Osteoma
Incidence 10% of benign tumors 3% of benign tumors

< 2 cm (typically <1.5cm)

>2 cm (average, 3.5 - 4.0 cm)
Site > 50 % in long bone diaphysis
> 35% in posterior elements of the spine
Location Proximal femur > tibia diaphysis > spine vetebral column > proximal humerus > hip
Natural History Self-limited Progressive

Benign appearance. No growth potential. Central nidus composed of more organized osteoid and lined by osteoblasts. 

Benign appearance. Localized growth, with aggressive potential. Central lesion less organized, with greater vascularity. 
Symptoms Nocturnal pain, relieved by NSAIDS Dull ache which is less likely to be relieved by NSAIDS (partial response). >50% of spine tumors have neurologic symptoms.
Management of Spine Lesions Nonsurgical management is indicated as first-line treatment.  Surgery is always indicated as they do not respond to nonsurgical treatment.

  • Nonoperative
    • observation
      • indications
        • rarely, if ever, indicated as the lesion will continue to grow
  • Operative
    • curettage or marginal excision with bone grafting
      • indications
        • standard of care
      • recurrence 10-20%
Image Bank
Bone scan
Case A prox. humerus
Case B prox. femur
Case C prox. femur
Case D spine
Case E calcaneus


Please rate topic.

Average 4.2 of 23 Ratings

Questions (3)
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Evidence (5)
Topic COMMENTS (4)
Private Note