|
Year |
2002 |
|---|---|
|
Question Number |
159 |
|
Category |
Orthopaedic Disease |
Question
A 69-year-old man reports the acute onset of nonradicular low back pain, and nonsurgical management results in pain resolution. A bone scan and CT scan are shown in Figures 41a and 41b. What is the most likely diagnosis?
1- Enostosis
2- Osteoid osteoma
3- Osteoblastoma
4- Osteosarcoma
5- Metastatic prostate carcinoma
Figures
Answer (click for answer)
Preferred Response: 1
Discussion:
Enostosis or bone island represents a focus of mature compact(cortical) bone found within the cancellous bone. It is a benign lesion which most likely represents a congenital or developmental process that occurs secondary to a failure of bone resorption during endochondral ossification. The diagnosis is typically made after the lesion is noted incidentally on plain radiograph. It appears as a homogenously dense, sclerotic focus in cancellous bone with radiating streaks or "thorns" that blend with the trabeculae of the normal bone. Clinically the patient is typically asymptomatic and the distinguishing characteristic of this diagnosis is that on bone scan the lesion is typically "cold."
Reference: Flemming DJ, Murphey MD, Carmichael BB, Bernard SA: Primary tumors of the spine. Semin Musculoskeletal Radiol 2000;4:299-320.