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Musculoskeletal Imaging

E3178. Atypical Locations of Osteoid Osteomas and Impact on Intervention

Kafer I,  Walsh P,  Brown M,  Coopersmith H. Northwell Health, Manhasset, NY

Address correspondence to P. Walsh (pamelajuliawalsh@gmail.com)

Background Information: Osteoid osteomas painful benign skeletal lesion seen in individuals ranging from 7 to 25 years-old, with a predilection for males. The typical presentation is nocturnal pain relieved by salicylates. Osteoid osteomas consist of a nidus surrounded by fibrovascular tissue and is usually accompanied by reactive sclerosis. The most common location for osteoid osteomas are intracortical and along the diaphysis of long bones. Medullary and subperiosteal locations are less frequent. While osteoid osteomas can have atypical locations with regards to the bone itself, these lesions can also be found in less common locations along the axial and appendicular skeleton. These atypical locations may make it difficult to diagnose an osteoid osteoma, as well as impact treatment. While surgical excision had been the primary mode of treatment symptomatic osteoid osteomas, radiofrequency ablation has become an increasingly frequent method of treatment. The location of the lesion within the bone as well as the location in the body needs to be taken into consideration and may modify usual treatment techniques. Our purpose is to demonstrate atypical locations of osteoid osteomas within the bone and along the skeleton and the impact it has on diagnosis and treatment methods.

Educational Goals/Teaching Points: • Illustrate and describe the components of an osteoid osteoma • Discuss the different locations of osteoid osteomas within the bone with examples: intracortical, intramedullary and subperiosteal • Show cases of osteoid osteomas in uncommon locations and discuss their impact on diagnosis and treatment • Review the different treatment options for osteoid osteomas and how the location of the lesion can change the interventional approach

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques: • The location of osteoid osteomas dictate what treatment options are available • Osteoid osteomas close to the skin or joint space risk damage during radiofrequency ablation • Special consideration needs to be taken into account when treating an osteoid osteoma located at the metaphysis/physis of a growing child • Osteoid osteomas in the spine need to be treated with caution due to proximity of the spinal canal and adjacent nerves • Intra-articular osteoid osteomas are technically challenging with regards to treatment and may be more prone to infection and ablation of non-intended tissues

Conclusion: Osteoid osteomas are not an uncommon disease entity and straightforward cases usually cause no issue. Atypical presentations of osteoid osteomas can create diagnostic and therapeutic challenges. It is important to be aware of the uncharacteristic locations of these lesions. Treatment options are often location dependent and the approach is determined by adjacent sensitive structures. Slight modifications of treatment procedures can help avoid unintended complications.