Osteoid Osteoma



Osteoid Osteoma


G. Petur Nielsen, MD

Andrew E. Rosenberg, MD










Coronal T2-weighted MR of the right hip shows a case of an osteoid osteoma on the surface of the bone. The tumor is obscured by extensive intramedullary, periosteal, and soft tissue edema (bright white areas).






Resected subperiosteal osteoid osteoma is well demarcated from the surrounding thick subperiosteal reactive bone. The oval nidus is red-tan and does not involve the medullary cavity.


TERMINOLOGY


Abbreviations



  • Osteoid osteoma (OO)


Definitions



  • Benign bone-forming tumor characterized by its small size, limited growth potential, classic pattern of pain, and composition of woven bone trabeculae rimmed by osteoblasts


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Accounts for 13% of all primary benign bone tumors and 3% of all other primary bone tumors


  • Age



    • Usually develops in adolescents and young adults



      • Peak incidence: 5-25 years (76%)


  • Gender



    • Male predominance (2-3:1)


Site



  • Long tubular bones (75% of cases)



    • Proximal femur is most common location


    • Lesions are located in diaphysis and metaphysis (65-80%) and infrequently epiphysis


    • Common in subperiosteal region and within cortex (70-80%); intramedullary lesions less frequent (25%), intraarticular tumors are unusual


  • Vertebral column (10-14% of cases)



    • Posterior elements (90%), body (10%)


  • Short tubular bones of hands and feet (8-10%)


Presentation



  • Severe localized pain that is often worse at night, which is relieved by aspirin or other nonsteroidal anti-inflammatory medication



    • High levels of prostaglandin E2 and prostacyclins within nidus osteoblasts


    • COX-2 overexpression by osteoblasts


  • Joint pain mimicking that of primary articular disorder when lesion is located close to or within joints


  • Swelling that may mimic infection, especially when arising in small bones of hands and feet


  • Joint effusions


  • Painful scoliosis due to spasm of paravertebral muscles



    • Most common cause of painful scoliosis


  • Overgrowth of bone when located near growth plate


  • Limp and limitation of range of motion


Treatment



  • Radiofrequency ablation has become treatment of choice in most instances



    • Improves local control, eliminates removal of normal tissue, and is outpatient procedure


  • Curettage, burr down, or en bloc resection in cases that cannot be treated with radiofrequency ablation due to proximity to vital structures



    • Lesions located in spine frequently require surgical removal


  • Medical therapy and observation in selected patients


Prognosis



  • Excellent, as lesion is not locally aggressive and does not metastasize


  • Local recurrence rate following radiofrequency ablation is approximately 0-25%


IMAGE FINDINGS


General Features



  • Lesion (nidus) is 1-2 cm in diameter


  • Nidus has well-defined margins and often contains variable, patchy, central mineralization


  • Nidus surrounded by subperiosteal or medullary reactive sclerosis with adjacent soft tissue edema




    • Extensive reactive changes may simulate a more aggressive neoplasm and obscure lesion


  • Lesion is usually solitary and rarely multifocal


Radiographic Findings



  • Round, radiolucent with central mineralization


  • Peripheral sclerosis frequent and may be extensive


MR Findings



  • Isodense to skeletal muscle on T1-weighted images


  • Lucent components and surrounding edema have increased signal intensity on T2-weighted images


CT Findings



  • Well-demarcated, small, round lesion with central mineralization, bordered by reactive bone


Bone Scan



  • Marked uptake of radionuclide


MACROSCOPIC FEATURES


General Features

Jul 6, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Osteoid Osteoma
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