Synonyms

OO

Category

Bone

Behaviour

Benign

Gender

Male

Tissue of Origin

Bone

Epidemiology

• Common Benign Bone-forming tumour (10% of Benign Bone tumours)
• Peak incidence in 2nd–3rd decades
• Male predominance (3:1)
• Nidus <1.5 cm by definition

Clinical Features

• Classic: nocturnal pain relieved by aspirin/NSAIDs (prostaglandin-mediated)
• Localised tenderness
• Painful scoliosis if spinal location (paravertebral muscle spasm)
• Growth arrest or limb length discrepancy in children

Location

• Proximal femur (most common)
• Tibia
• Spine (posterior elements)
• Small Bones of hands and feet

Imaging

• Small lucent nidus (<1.5 cm) with surrounding dense reactive sclerosis on X-ray/CT
• CT is gold standard - best demonstrates nidus
• Bone scan: intensely hot ('double density sign')
• MRI: extensive surrounding oedema - nidus may be missed without CT correlation

Pathology

• Well-defined nidus of osteoid trabeculae and osteoblasts within Vascular Fibrous stroma
• Surrounding dense reactive Bone
• Prostaglandin E2 production by nidus causes pain
• No Malignant potential

Genetics

• No specific mutations identified
• FOS rearrangements reported in some cases
• Benign self-limiting lesion

Treatment

• CT-guided radiofrequency ablation (RFA) - first-line, minimally invasive, >90% success rate
• NSAIDs - symptom control; lesion may spontaneously resolve over 3–7 years
• Surgical excision for lesions not amenable to RFA
• Laser ablation: alternative to RFA

Prognosis

• Excellent - self-limiting Benign lesion
• Spontaneous resolution over 3–7 years
• RFA: >90% cure rate with single treatment
• No Malignant transformation

Key Points

• Nocturnal pain relieved by aspirin/NSAIDs is virtually pathognomonic
• CT is essential to identify the nidus - MRI alone is unreliable due to surrounding oedema
• CT-guided RFA is the treatment of choice - safe, effective, minimal recovery time
• Spinal lesions cause painful scoliosis which resolves after treatment

Workup - Blood Tests

No blood tests required

Workup - Local Imaging

• Plain radiograph
• CT - gold standard; precise nidus localisation for surgery or ablation
• MRI - may appear nonspecific; not first-line

Workup - Biopsy

• Biopsy rarely required if imaging characteristic
• Histology (if obtained): osteoid and Bone with surrounding Vascular and fibroblastic tissue

Workup - Staging

No staging required

Follow-up Summary

• Year 1: Post-operative visit within first 6 weeks; 3–6 monthly clinical examination and plain films of primary site
• Years 2–3: 6-monthly clinical examination and plain films of primary site
• Discharge 3 years after surgery