Osteoid Osteoma Differential Diagnoses

Updated: Aug 12, 2021
  • Author: Gerard Librodo, MD; Chief Editor: Harris Gellman, MD  more...
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Diagnostic Considerations

Clinical picture

Patients with osteoid osteoma can present with an atypical history and lesions in unusual locations (see Presentation). Because of this presentation, osteoid osteomas can be confused with osteomyelitis, especially Brodie abscesseseosinophilic granulomas, and other benign cysts.

Radiographic appearance

Radiographic findings of osteoid osteoma (see Workup) may mimic those of stress fractures, intracortical abscesses, sclerosing osteomyelitis of Garré, or avascular necrosis. It should be differentiated from osteochondritis dissecans and inflammatory arthritis. On rare occasions, it can resemble osteosarcoma.

Features on bone scanning

Histologically, osteoid osteoma is almost identical to osteoblastoma, osteosarcoma, and enostosis. However, benign osteoblastoma has a uniform pattern of thick, closely packed trabeculae with increased cellularity and vascularity. Osteosarcoma and parosteal osteosarcoma are more cellular than osteoid osteoma, and they are anaplastic with elaborate malignant osteoid. Enostosis, on the contrary, represents the opposite extreme, with islands of densely packed, thickened bone trabeculae with normal stroma. [33]

Delays of 11.8-36 months have been reported in the diagnosis and treatment of osteoid osteoma. Pettine et al noted that bone scanning dramatically decreased the mean interval from the appearance of symptoms to diagnosis from 35 months to 12 months. [13]

Histologic appearance

Osteoid osteoma can appear as spondylolysis on bone scans; both can appear as abnormal activity in the spine. Wells et al noted that in cases of spondylolysis, immediate postinjection images showed minimal or no abnormal activity, but abnormal activity was observed when imaging was delayed after the injection. [17]  Early uptake of tracer is detectable in all cases of osteoid osteoma. Delayed images reveal unilateral or bilateral abnormalities in cases of spondylolysis but demonstrate intense tracer accumulation in cases of osteoid osteoma. [34]