Osteoid Osteoma

Original Editors - Michelle Quill from Bellarmine University's Pathophysiology of Complex Patient Problems project.

Top Contributors - Jacquelyn Moriah Facktor, Elaine Lonnemann, Admin, Chad Simmons, Michelle Quill, 127.0.0.1, WikiSysop, Rachael Lowe, Vidya Acharya, Wendy Walker and Kim Jackson  

Definition/Description

Benign osteoblastic tumor consisting of vascular osteoid tissue centrally and sclerotic bone peripherally. This type of tumor is commonly found in the diaphysis of long bones such as the femur (more than 50% of cases). This type of tumor can also occur more rarely in the bones of the hands, feet, and posterior spine.

A benign osteoblastic tumor consisting of vascular osteoid tissue centrally called the Nidus and sclerotic bone peripherally. Osteoid Osteoma does not grow or behave in a locally aggressive manner, and it has no potential for malignant transformation.[9] May initially appear on a radiograph as a small sclerotic bone island within a circular lucency.[8] In >50% of cases, the lesion occurs in the metaphysis and diaphysis of the long bones, particularly the femur and tibia. Other anatomic sites of involvement include the spine, upper extremity, pelvis, sacrum, ribs, hands, and feet.[1][2][9]

Prevalence

Osteoid osteomas account for 1/8 to 1/10 of symptomatic bone tumors and 5% of all primary bone tumors.

Osteoid osteomas occur in children and young adults between the ages of 7 and 25. This type of bone tumor also occurs two to three times more often in males than in females.

Characteristics/Clinical Presentation

This type of tumor is commonly found in the diaphysis of long bones (proximal femur), hands and feet, and posterior elements of the spine (lamina and spinouse processes).

Clinical presentation is typically pain in the area of the tumor described as a dull ache, pain that is worse at night, increased skin temperature, sweating and tenderness to palpation of the localized area. Pain is relieved by salicylates or aspirin.

Ninety percent of cases occur in patients younger than 25 years so osteoid osteomas can easily be mis-diagnosed as a musculoskeletal disorder because when someone in their twenties reports pain, the vast majority of people assume the pain is musculoskeletal in nature. The true diagnosis is so easily overl ooked because epiphyseal lesions mimic intra-articular derangement and pain is typically localized to the site of the lesion, so the location of pain can be anywhere, and may coincide with common sites of musculoskeletal inflammation or strain. Another reason diagnosis is easily misled is that pain usually occurs before the lesions are visible on radiographs and in the early stages can be easily missed on a radiograph. Finally, these lesions may be associated with proliferative synovitis due to prostaglandin secretion that decreases range of motion, creates joint effusion, and can mimic inflammatory arthritis.

Associated Comorbidities

None

Medications

Pain caused by osteoid osteomas can be relieved with aspirin and NSAIDS, which inhibit the prostraglandins released by the tumor cells. Prostaglandins cause changes in vascular pressure, which stimulates sensory nerve endings locally, causing pain. Inhibition of these prostaglandins relieves pain.

Diagnostic Tests/Lab Tests/Lab Values

Radiograph reveals a well demarcated area of translucency (nidus) inside the bone, often times with a central calcified dot. This is surrounded by bony sclerosis. Usually less than 1 cm in size

An osteoid osteoma can also be detected with bone scan, or scintigraphy, which will show a focal uptake of the radiotracer by the tumor.Scintigraphy is often used to detect an osteoid osteoma that is not easily seen on a radiograph, such as a vertebral tumor.

Osteoid osteomas can be detected on an MRI and CT scan, which are often used to identify the location of the nidus when the tumor is intra-articular. A CT scan will reveal the nidius as a small area of low attenuation surrounded by reactive bone formation, seen as a larger area of higher attenuation.

Causes

An ostoid osteoma is a vascular lesion consisting of an area of immature bone surrounded by osteoblasts and osteoclasts. The tumor starts with the nidus, or nest of vascular osteoid tissue in the center of the tumor. The nidus then becomes surrounded by reactive bone sclerosis. After the removal of the nidus, the secondary bone sclerosis generally disappears gradually.

Systemic Involvement

Systemic involvement is uncommon with an osteoid osteoma.

Medical Management (current best evidence)

Treatment options include medical management with NSAIDs, surgical excision (wide/enbloc excision or curetting), or the use of CT- or MRI-guided minimally invasive procedures including core drill excision, laser photocoagulation, or radiofrequency ablation. For many years, complete surgical excision was the classic treatment of osteomas, usually performed in patients with pain despite medical management.

Physical Therapy Management (current best evidence)

None

Case Reports

www.uhrad.com/msiarc/msi084.htm

Recent Related Research (from Pubmed)

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