Osteoid Osteoma
February 14, 2021
| By :
OrthoFixar
|
Orthopedic Pathology
- Osteoid osteoma is a self-limiting benign bone tumor.
- It’s one of three bone tumors in which tumor cells produce osteoid:
- Osteoid osteoma
- Osteoblastoma
- Osteosarcoma.
Epidemiology
- Most osteoid osteomas occurs in the second or third decades of life (< 30 years old).
- Male > female (3:1).
- The tumor usually found in cortical bone, (It can also be found in cancellous bone).
- Common locations include diaphyseal bone, proximal femur, tibia, and spine.
Clinical Evaluation
- The patient with an osteoid osteoma has pain that is worsen at night and is relieved by aspirin or other nonsteroidal anti-inflammatory medications (NSAIDs).
- Maybe due to increased levels of cyclooxygenases and prostaglandins that have been found in the lesion.
- When the tumor is near a joint, swelling, stiffness, and contracture may occur.
- May produce painful non-structural scoliosis in adolescent.
- The Osteoid osteoma found on the side of concavity.
- This is thought to result from marked para vertebral muscle spasm.
Imaging Evaluation
- Imaging studies usually are diagnostic.
- Plain radiographs often are sufficient to make the diagnosis.
- The lesion consists of a small (<1.5 cm) central radiolucent nidus with surrounding bony sclerosis.
- Computed tomography CT is the best study to identify the nidus and confirm the diagnosis.
- It demonstrates better contrast between the lucent nidus and reactive bone.
- Technetium bone scans always show intense focal uptake.
- Double density sign which if present is highly specific and helpful in distinguishing it from osteomyelitis.
- Ultrasound: focal cortical irregularity with adjacent hypoechoic synovitis may be present at the site of intra-articular lesions.
- MRI usually shows extensive surrounding edema.
The double density sign, also sometimes referred to as the hotter spot within hot area sign. It refers to a central focus of intense uptake (the nidus) within a surrounding lower, but nonetheless increased uptake(the rim).
Histology Findings
- Fibrovascular tissue with immature bony trabeculae that are rimmed by
prominent osteoblasts, and surrounded by a sclerotic rim. - It’s appears similar to osteoblastoma (osteoblastomas are larger).
The osteoid osteoma is composed of three concentric parts:
1. Nidus
2. Fibrovascular rim
3. Surrounding reactive sclerosis
Differential Diagnosis
- Long bones lesions differential diagnosis are:
- Enostoses (bone island)
- Stress fracture.
- Osteomyelitis (Brodie abscess).
- Cortical desmoid
- Osteochondroma
- Osteosarcoma
- Posterior spinal lesions differential diagnosis are:
- Aneurysmal bone cyst.
- Osteoblastoma.
OSTEOID OSTEOMA | OSTEOBLASTOMA | |
---|---|---|
Presentation | – Diurnal pain pattern/night pain – Pain relieved by aspirin/NSAIDs | – Random pain pattern – Pain not relieved by aspirin/NSAIDs |
Imaging | – Central radiolucent nidus < 1 cm Large secondary bone reaction – Characteristic “target” appearance | – Central radiolucent nidus > 2 cm – Minimal secondary bone reaction gives lesion a more aggressive appearance |
Location | Diaphyseal (typical) | – Diaphyseal or metaphyseal – Posterior spine elements |
Growth pattern | Self-limited growth pattern | Unlimited growth pattern |
Treatment | – Radiofrequency ablation (RFA) – Surgery if tumor is close to nerve or vessels (e.g., spine) | Intralesional excision |
Treatment
Non-Operative treatment:
- Indications:
- The patient’s symptoms are adequately controlled.
- The patient is willing to undergo long term medical management.
- Anti-inflammatory medication can be used as the definitive treatment.
- Patients treated in this manner usually experience spontaneous healing of the lesion within 3 to 4 years.
Operative treatment:
- CT scan–guided RFA:
- It’s the dominant method of treatment.
- Indications:
- Failure of medical management
- Most patients with lesions of the pelvis or long bones of the extremities.
- Contraindication:
- A lesion close to a critical structure (i.e., neurovascular bundle or spinal cord) is a to RFA.
- A radiofrequency probe is placed into the lesion, and the nidus is heated to 80-90°C.
- It usually is done as an outpatient procedure, and patients usually can return immediately to full activity.
- Recurrence rates are less than 10%.
- Open surgical removal:
- Indication:
- Failure of medical management
- A lesion close to a critical structure (i.e., neurovascular bundle or spinal cord).
- Removal of the entire nidus, this can be accomplished by curettage or en bloc resection.
- Recurrence rates with this technique are less than 10%.
- Indication:
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