Osteoid osteoma is a benign bone-forming tumor characterized by small size limited growth potential and disproportionate pain.

Osteoid osteoma accounts for about 10% of benign bone tumors and 2 to 3% of all primary bone neoplasm.

The exact cause of osteoid osteoma remains unknown.

Osteoid osteoma has a nidus 1.5 to 2cm that consists of osteoid, osteoblast, and a variable amount of fibrovascular stroma. The nidus is surrounded by an area of dense reactive bone.

Osteoid osteoma is characteristically seen in children and adolescents.

Typically presents with a history of dull aching pain in the region overlying the affected long bone.

These symptoms will be present for several months, tends worse at night, and significantly relieved by salicylates or NSAIDs.

The most commonly involved site is the metaphyseal or diaphyseal region of femur and tibia.

Limp is often noted during the evaluation and muscle wasting is apparent in long-standing cases.

Plain radiographic orthogonal views of the affected bone are necessary to suspect the osteoid osteoma.

Computed tomography demonstrates a cortical lesion with a bull’s eye lesion – Central nidus surrounded by reactive bone.

The biopsy confirms the diagnosis of osteoid osteoma.

Osteoid osteoma is described as a self-limiting lesion that may mature spontaneously over for a year. Non-surgical treatment includes salicylates and NSAIDs.

Less invasion treatment is indicated in children with persistent symptoms. It includes CT guided percutaneous radiofrequency ablation.

The open procedure is indicated when histology remains doubtful, repeated failure of the minimally invasive ablative procedure and when the neurovascular structure is within 1.5cm from the lesion.

The open procedure includes en bloc excision of the lesion and prophylactic stabilization of bone.

Osteoid osteoma rarely produces any long term consequences.

Very rarely it can lead to limb length discrepancy.