Osteoblastoma

Osteoblastoma, histology of osteoblastoma at low magnification
Histology of osteoblastoma at low magnification. Image by Nephron, Wikimedia Commons, CC BY-SA 3.0.

Definition

  • Benign bone forming tumour histologically similar to osteoid osteoma but over 2 cm
  • About 1% of primary bone tumours
  • Can behave aggressively, with an epithelioid variant that may mimic osteosarcoma

Epidemiology

  • Age 10 to 30 years
  • Male predominance, about 2 to 1
  • About 40% arise in the posterior elements of the spine
  • Long bones are next most common, often diaphyseal or metaphyseal
  • Rare in the small bones of hands and feet

Clinical Features

  • Dull pain, less night pain and less NSAID response than osteoid osteoma
  • Painful scoliosis and nerve root symptoms in spinal lesions
  • Swelling and tenderness in superficial sites
  • Neurological deficit from spinal canal extension

Investigations

Axial CT of an osteoblastoma of the C7 vertebra
Axial CT of an osteoblastoma of the C7 vertebra. Image by Li Z, Zhao Y et al., Wikimedia Commons, CC BY-SA 4.0.
  • Expansile lytic lesion with central mineralisation
  • CT defines cortical breach and spinal extent
  • Biopsy to exclude osteosarcoma
  • Bone scan shows intense uptake
  • MRI shows surrounding oedema and soft tissue extension
  • Histology shows osteoid and woven bone rimmed by osteoblasts, without the permeative growth of osteosarcoma

Management

  • Extended curettage with adjuvant and bone grafting, or en bloc excision
  • Recurrence up to about 20% after curettage
  • Stabilise the spine if resection causes instability
  • Radiofrequency ablation is less suitable than for osteoid osteoma because of size
  • Embolisation before surgery for vascular spinal lesions

Differential Diagnosis

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.