• Locally aggressive tumor
  • Histologically similar osteoid osteoma distinguished by a size >1.5 cm
  • Possible extra-osseous extension
  • < 30 years age
  • M:F = 2-3:1
  • Pain is not acute or severe. Not relieved by NSAIDs
  • Femur and tibia commonest locations 
  • Arise in medullary cavity
  • Mostly in appendicular skeleton
  • 30-40% in posterior elements of spine
  • Rarely metastasizes
  • Predominantly lytic
  • > 2 cm in diameter
  • Larger lesions show greater matrix mineralization
  • Sclerotic margin in 90% cases
  • CT: occult calcification which is punctate, nodular or generalized
  • Can cause extra-cortical mass (reactive or tumor extension)
  • Positive in scintigraphy
  • MRI: low to intermediate signal on T1, high signal on T2/STIR. Heterogeneous post contrast enhancement. Secondary ABC can show fluid-fluid levels
  • Differentials: Brodie abscess and LCH
Read more

Kroon, Herman M., and J. Schurmans. “Osteoblastoma: clinical and radiologic findings in 98 new cases.” Radiology 175.3 (1990): 783-790.

Shah, Jignesh N., et al. “Pediatric benign bone tumors: what does the radiologist need to know?: pediatric imaging.” RadioGraphics 37.3 (2017): 1001-1002.