Osteoid osteoma


A benign lesion characterized by a richly innervated nidus less than 1.5cm in diameter that consists of primitive woven bone and osteoid. 


First described in 1930.

Name coined by Jaffe in 1935


11% of benign bone tumors

70% of pts less than 20

Rare under 5 or over 40

M>F 2:1

Usually solitary


Bone involvement:              

-femur                    30%

-Tibia                     27%

-Humerus              10%

-Spine                      7%

-Talus                      4%

In the spine the pedicles are most often involved

Tends to occur at the end of the diaphysis




Pain, which is worse at night, or after alcohol (due to vasodilatation)

The pain is mediated by prostaglandins and responds rapidly to aspirin

May be asymptomatic, particularly if located in the hand

Can be accompanied by muscle atrophy, a limp, painful scoliosis, synovitis, or abnormalities of bone growth including limb lengthening

Osteoid osteoma is the commonest cause of a painful scoliosis

May be associated with a mild leucocytosis


A dense sclerotic area in a paracortical region with a central lytic nidus

Sharply round or ovoid

Usually less than 1cm; by definition less than 1.5 cm (McLeod in Dahlin’s)

Curetted material on XR has a very fine trabecular pattern

CT best for showing the small central nidus (like a target)


Gross:     Well demarcated nodule, often cherry red but occasionally very dense and white

Micro:    -maze of small spicules of immature bone most often lined with prominent osteoblasts and osteoclasts

                -No cartilage matrix formation

                -i.e. the tumour is made up of a nidus of well vascularized osteoid

Differential diagnosis


Bone island

Eosinophilic granuloma



Stress fracture


The natural history is one of spontaneous resolution over the course of several years.


Prostaglandin inhibitors have been shown to work but take a long time, e.g Anti-inflammatory meds or Aspirin


The nidus is first localized (preferably with CT scan)

The present technique of choice is the burr down technique.  This preserves the reactive bone around the lesion and reduces the risk of fracture.

Percutaneous methods using CT guided drills or percutaneous radiofrequency electrodes don’t provide pathological material

Perc Radiofrequency has been shown to have equal outcomes to surgery.

Intraoperative nuclear scanning using a hand held Geiger counter can be used to confirm complete removal of the nidus.