• Night pain
• Children
• Sclerotic lesion with lytic nidus
Interse surrounding sclerosis (which may involve adjacent bones) makes for a very typical appearance
Periosteal reaction common except for intraarticular variant, which presents with synovitis.
Intense soft tissue oedema on MR & CT
CT shows nidus best
Night pain is the typical presenting complaint
The spine is also a common location
• Like osteoid osteoma but larger
• Especially spine where can cross vertebrae
• Speckled ossification
Spine commonest location
Well defined non sclerotic rim
Sclerosis present in surounding bone
Periosteal reaction if close to cortex, this may have several patterns sometimes bizarre
One third show matrix ossification
Often diaphyseal when in long bones
MR associated with marked soft tissue oedema and sclerosis in surrounding bones
Said to be similar to osteoid osteomalacia just larger, however probably also biologically different
Has an aggressive variant
• Dense bone
• Skull
Paranasal sinuses and skull typical
Rare in long bones
Often incidental findings
Can block simus draininage if large
Dense bone on imaging
On surface of bone
No medullary communication
May be associated with Gardners syndrome
(polyposis, dentigerous cysts, epidermoid custs, desmoid tumours, skin fibromas)
Protrudes from bone so easy to distinguish from other lesions.
Medullary continuity must be present. If not consider BPOP
Cartilage cap and bursa may be present.
Cap thickness should not exceed 15mm