Osteoid OsteomaDz

Definition: A benign tumor usually affecting long bones.

ICD-9 Code: M9191/0

Pathology: Lesions are typically small (<1.5 cm), round, and characterized as a central core (or nidus) of highly vascularized immature bone and osteoid tissue.

Demographics: One of the more common benign tumors of bone. More frequently affects young boys (3:1 male:female ratio). Typically affects older children and young adults (7–25 years). It is rare after age 30.

Cardinal Findings: Most patients present with localized dull pain or aching, often maximal at night, worse with alcohol ingestion and are not relieved by rest but may be improved by NSAIDs or aspirin. Most common sites include long bones (femur, tibia) and less commonly in the hands or feet. These arise in the shaft or near metaphysis and are particularly common in the neck of the femur or intertrochanteric region.

Uncommon Findings: Intraarticular osteoid osteomas may present as chronic monarthritis with synovitis. Uncommonly they are found in vertebral bodies as a cause of low back pain.

Imaging: Early on, plain radiographs are often normal but with time, a central nidus of osteolysis appears as a radiolucent core and is surrounded by a halo of reactive/sclerotic bone. The diagnosis may be made earlier with the use of scintigraphy (increased uptake) or CT. A normal bone scan excludes osteoid osteoma. MRI may be helpful in intracortical lesions but is not superior to the methods cited.

Keys to Diagnosis: Chronic focal pain, worse at night, should prompt imaging evaluation. There are no diagnostic laboratory tests. It can be detected by radiography, scintigraphy, or CT. Diagnosis can be confirmed by CT-guided needle biopsy or, preferably, MRI-guided biopsy and ablation

Differential Diagnosis: It must be differentiated from osteomyelitis, Brodie’s abscess of bone, stress fracture, and other tumors of bone (i.e., osteosarcoma, osteoblastoma).

Therapy: Aspirin, nonselective NSAIDs, and COX-2 inhibitors are often effective at improving symptoms. MRI-guided, percutaneous interstitial laser ablation (photocoagulation) is becoming the less invasive treatment of choice. Where interventional methods are not available, surgery may be effective. Some lesions will regress without ablation or excision.

BIBLIOGRAPHY

Dixon J. Tumors of bone. In: Hochberg MC, Silman AJ, Smolen JS, et al., eds. Rheumatology, 3rd ed. Edinburgh: Mosby, 2003:2186–2187.

Westhovens R, Dequeker J. Musculoskeletal manifestations of benign and malignant tumors of bone. Curr Opin Rheumatol 2003;15:70–75.PMID:12496513