Osteoblastoma

Original Editors - Michelle Laine & Melanie Stippler from Bellarmine University's Pathophysiology of Complex Patient Problems project.

Top Contributors - Michelle Laine, Admin, Elaine Lonnemann, WikiSysop, Evan Thomas, Alli Castagno, Wendy Walker and Kim Jackson

Definition/Description

Osteoblastoma is a rare, benign osteoblastic (bone) tumor that most commonly develops in the spine, sacrum, long bones, and flat bones. Benign tumors do not spread to various sites or organs. However, an aggressive type of osteoblastoma has been identified in very rare occasions that have led to metastasis, death, and mimicked osteosarcoma. It is a bone tumor that histologically is very similar to that as an osteoid osteoma, which can make differentiating between the two difficult. Osteoblastoma tumors are typically larger, and have an osteolytic and sclerotic border when viewed on radiographs.

Prevalence

Of all benign bone tumors, osteoblastoma only accounts for about 1-2%, being more prevalent in males than females. This more commonly develops in men younger than 30, but can occur in ages as young as 2 and old as 70. Of those diagnosed with osteoblastoma, 80% of them are within the ages of 10 and 30.

Osteosarcomas are 20 times more likely to occur, while osteoid osteomas are 4 times more likely to occur than osteoblastomas.

Characteristics/Clinical Presentation

Signs and Symptoms:

• Pain(most common symptom)
  • Worsens with time
  • Less severe night pain when compared to osteoid osteoma
  • NSAIDs do not have an effect on pain levels, like with osteoid osteoma
• Tenderness over the lesion
• Swelling at the lesion
• Bony enlargement over lesion with palpation
• Scoliosis of the spine
• Muscle spasms
• Decreased ROM
• Neurological symptoms secondary to spine lesions causing change in the bony structure
  • 50% of those diagnosed with spinal lesions report neurological symptoms
    

Associated Co-morbidities

None.

Medications

None.

Diagnostic Tests/Lab Tests/Lab Values

• X-Ray
  • Positive for Osteoblastoma: 4-6cm in size at the lesion, cortical thinning, expansion of bone, radiolucency in the central aspect of the lesion with a thin, sclerotic border, may also have soap bubble appearance and osteolytic expansive lesion similar to that of aneurysmal bone cyst
• CT Scan / MRI
  • CT scan and MRI are both helpful in identifying the lesion and the extent of tissue involved in the lesion
• Bone Scan
  • Positive for Osteoblastoma: increase in uptake would be noted
• Bone Biopsy
  • Fragment of the bone removed from tumor and sent to lab for diagnostic testing/histological report
• Blood Work – Complete Blood Count (CBC)
  • Helpful for differential diagnosis in determining if the lesion is of another form of benign or malignant bony tumor
• Chest X-Ray
  • Used for differential diagnosis of osteosarcoma

Etiology/Causes

Currently unknown.

Systemic Involvement

Benign tumors do not spread to various sites or organs.

Medical Management (current best evidence)

In 90-95% cases, individuals are cured following the initial treatment, but there are about 10% of cases that have recurring lesions/tumors.

En bloc resection

• Removal of the bone containing the tumor via surgery. In some cases, internal fixation may be warranted.

Curettage/Bone Grafting

• Scraping of the tumor using a curette. This may be medical treatment of choice when tumor cannot be removed by bone removal.
• Following scraping, an allograft (donor bone tissue) or autograft (bone taken from another bone) may be used to fill the hole.

Embolization

• Alternative non-surgical method.
• Blocks blood flow in order to reduce the size of the tumor.
• If this method does not work, surgical intervention can then be used within 24 hours of this procedure.
  

In cases with reoccurring lesions/tumors, there is a risk that they may develop or transform into a more serious type of bone tumor, such as aggressive osteoblastoma or osteosarcoma. At this point, alternative medical implications may be indicated:

• Chemotherapy or Radiation Therapy
  

Physical Therapy Management (current best evidence)

Post-Surgical Treatment:

• Strengthening
• ROM
• Posture
• Flexibility
• Proprioception/Balance/Coordination
• Gait
• Wound Care
• Education
  

Differential Diagnosis

Condition:	Differentiating Signs/Symptoms:
Aggressive Osteoblastoma	More common in older populations. Present with a more aggressive local behavior and higher re-occurrence rate after initial removal.
Osteosarcoma	Malignant bone tumor that almost always originates in the metaphysis of long bones (LE's). It commonly will have early metastasis to the lungs. Osteosarcomas are rapidly growing lesions that commonly develop during adolescent growth spurts. In the older populations this is known as Paget’s Disease.
Osteoid Osteoma	Commonly found in similar age group as osteoblastoma. It is also a benign tumor of the bone. Patients present with intense, localized pain that worsens at night. Pain can be relieved by aspirin or NSAID. X-ray results would show a tumor smaller than osteoblastoma in size, < 2 cm in diameter. X-rays may not show bone changes months or years after the patient’s symptoms have began. The borders, on X-ray, appear more sclerotic and may have a central calcified dot.
Giant Cell Tumor	Rare, aggressive benign tumor that occurs in adults between ages of 20-40 years. Most tumors occur in the epiphysis, around the knee joint, femur, tibia, wrist, hip, shoulder, and low back. In rare cases, the tumor may spread to the lungs. Pain usually occurs in the area of the tumor. Patients will commonly complain of increase pain with activity and a decrease with rest. Pain comes on mildly at first, but then progressives. At the tumor site, painless swelling may be prominent.
Aneurysmal Bone Cyst	A benign, blood filled fibrous tumor – cyst that generally forms in teenagers. Most common sites are the knee and vertebrae, but can be found in any bone. Has been seen to increase the risk of bone fractures. These can be cured with surgery, but there is high re-occurrence rate. Patients commonly complain of pain with swelling, palpable mass, and neurologic changes (when spine involved). There are two forms: Active – confined in the bone, andAggressive – extends to nearby soft CT

Case Reports/ Case Studies

• Long-standing pain in a 25-year-old patient with a non-diagnosed cervical osteoblastoma: a case report.
  
• Treatment of osteoblastoma at C7: a multidisciplinary approach. A case report and review of the literature
  
• Osteoblastoma of the scaphoid bone – A rare case report
  
• A rare occurrence of osteoblastoma in a child

Resources

• Boston Children's Hospital
  
• American Academy of Orthopaedic Surgeons
• Atlas of Genetics and Cytogenetics in Oncology and Haematology