CASE 10
By: Dr. Saleh Othman, MD, MSc, JMCB
HISTORY: A 14-year-old male patient presented with right leg pain of one year’s duration. The pain was worse at night but was fully relieved by aspirin. There is no history of trauma.
What are your findings?
What is you’re your differential diagnosis?
FINDINGS:
Focal area of increased blood pool and tracer uptake in mid shaft of right femur typical appearance of osteoid osteoma.
DIFFERENTIAL DIAGNOSIS:
Acute osteomyelitis.
Trauma.
Osteoid osteoma.
PEARLS AND DISCUSSION:
Osteoid osteoma: It forms 10% of benign bone tumors and affects males twice than females. The age of affected patient ranges from 10 to 25 years.
The presenting symptoms are pain worse at night relieved with NSAD, increased skin temperature, tenderness in affected region. The most commonly affected sites are proximal femur, diaphysis of long bones, foot and spine.
On plain radiograph the tumor appears as radiolucent nidus surrounded by cortical sclerosis. On three phase bone scan it appears as nidus of increased blood pool surrounded by area of increased uptake on delayed imaging.
Teaching points:
The value of bone scan in osteoid osteoma is:
Clinical suspicion but negative x-ray.
Assessment of complete removal of the lesion by imaging the specimen removed by showing normal margin of bone.
Detection of local recurrence.
Bone scan sensitivity 100%.
FURTHER READING:
Radiol Clin North Am 1993; Brown ML. Bone scintigraphy in benign and malignant tumors. 31(4):731-8. Review.
AJR 2012; mIyer RS, et al. Pediatric bone imaging: diagnostic imaging of osteoid osteoma. 198: 1039-1052
