oncology
Osteoid Osteoma
intermediate
6 min
28 marks
6 questions
Clinical Scenario
A 14-year-old boy presents with 6 months of left thigh pain that is worse at night and dramatically relieved by aspirin. He has been waking at 2am with severe pain. On examination, there is localized tenderness over the proximal femur. There is no swelling or mass. X-ray shows cortical thickening in the proximal femur. CT scan reveals a <1cm lucent nidus with surrounding sclerosis.
Axial CT scan of the proximal femur demonstrating a classic osteoid osteoma. The central lucent nidus (<1.5cm) is visible with surrounding reactive sclerosis. The nidus may show central calcification. The cortical location with focal thickening is characteristic. Bone scan shows intense uptake (double-density sign). Treatment options include NSAID trial, CT-guided radiofrequency ablation, or surgical excision.
Image source: Open Access medical literature (NIH/PubMed Central) • CC-BY License
Questions
Question 1 (4 marks)
Describe the clinical features and typical presentation of osteoid osteoma.
Question 2 (5 marks)
What are the imaging features and how do you differentiate from other conditions?
Question 3 (6 marks)
Describe the treatment options and their success rates.
Question 4 (5 marks)
Compare osteoid osteoma and osteoblastoma.
Question 5 (4 marks)
Discuss special locations and their implications.
Question 6 (4 marks)
What are the outcomes and complications of treatment?
Exam Day Cheat Sheet
Must Mention
- •Age 10-35, male 2-3:1
- •Classic: night pain relieved by NSAIDs
- •Nidus <1.5cm (osteoblastoma >2cm)
- •CT is gold standard imaging
- •Prostaglandin-mediated pain
- •RFA 90-95% success rate
Common Pitfalls
- •Confusing with osteoblastoma
- •Wrong size criterion
- •MRI over CT
- •Missing intra-articular
- •Not knowing prostaglandins
- •Wrong RFA success rate