Atypical osteoid osteomas.

Osteoid osteoma is a very painful benign bone tumor that affects young adults. It is exceptional before 5 and after 30 years of age. It can be seen in any part of the skeleton. Presentation of the tumor may be intracortical, juxta-cortical or cancellous. In long bones, the tumor is frequently intracortical, and in the spine, it is usually located at the posterior elements. Osteoid osteomas having radiologic and clinical features other than classical presentation of osteoid osteoma are called atypical osteoid osteomas. Atypical osteoid osteomas are important because the diagnosis and treatment are often complicated in these cases. Misdiagnosis with prolonged impairment and sometimes overtreatment appears as a major problem concerning atypical osteoid osteomas. This paper gives brief general information about the classical presentation of osteoid osteoma, discusses the pathogenesis of the lesion and focuses on the clinical presentation, radiologic features and characteristics of atypical osteoid osteomas as well as their treatment modalities.