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Osteoid Osteoma

  1. It is commonest true benign bone tumor, exceded in incidence only be osteochondroma and nonossifying fibroma.
  2. Mostly occurs in children, adolescents or adults <30 years old, with male preponderance (M : F = 2 : 1).
  3. Cause symptoms out of all proportion to its size. That is mostly pain worse at night and relieved by aspirin (or NSAID’s)
  4. Any bone except skull may be affected but most (>50%) cases occur in femur or tibia
  5. It is small bone forming tumor consisting of a central nidus less than 2 cm in diameter containing osteoid, osteoblast, osteoclast & fibrovascular stroma. The nidus is surrounded by reactive sclerotic bone formation.
  6. There is no risk of malignant transformation.
  7. On x-ray there is a small radio lucent area (nidus) surrounded by dense sclerosis and cortical thickening, when the lesion is diaphysis. Occasionaly diaphyseal lesions becomes so sclerotic that there is no radiological evidence of nidus. In these instances CT scan is procedure of choice to identify nidus. CT scan help in exact localization of nidus.

  1. Tc 99- HDP bone scan reveal increased uptake in nidus.
  2. Treatment is excision along with nidus, en bloc resection, burr down technique and latest treatment is radiofrequency ablation (RFA).


  1. Benign aggressive tumor
  2. Big brother of ostoid ostoma (Nidus size more than 2 cm)
  3. Pain not relief by NSAID
  4. Spine posterier element common site
  5. May present with scoliosis / torticollis / radiculopathy.

Description: osteoblastoma7  Description: X-ray: Osteoblastoma of Proximal Phalanx

Non Ossifying Fibroma/Fibrous Cortical Defect


It is commonest benign lesion (not tumor) of bone found in 30- 50% of all children over 2years of age. (but most cases do not present clinically).

Etio - Pathology

  1. It is a developmental defect in which nest of fibrous tissue appears with in bone and persists for some years before ossifying.
  2. Histologically two basic components are benign fibro blasts arranged in pinwheel/ storiform/ whirled/ radiating bundles and osteoclast like gaint cell. Foamy pale histiocytes (macrophage), focal haemorrhage and hemosiderin pigment ( brown colour) may also be extensively present. So this cystic appearing lesion (on x-ray) is solid containing fibrous tissue and giant cell.

Clinical presentation

  1. Commonly discovered incidentally on plain x-ray. They rarely appears in children younger than 2 years or in adults over 20 years of age.
  2. They develop in metaphysis of long bones particularly femur and tibia. And mostly adjacent to or with in the cortex (i.e. are eccenteric), hence the name fibrous cortical metaphyseal endosteal defect.

  1. When patient nears skeletal maturity most lesions ossify or completely disappear But some cases not only persist but increase in size , penetrate in medullary canal & become symptomatic producing pathological fracture. These larger lesions are nonossifying fibroma.
  2. Treatment of choice observation. Curettage and bone grafting in symptomatic patient.

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