Presentation
Pain in the right knee that is worse at night and is relieved by non-steroidal anti-inflammatory drugs over a few months.
Patient Data
There is a small well-circumscribed radiolucent round region in the anterior medial aspect of the proximal tibial epiphysis.
There is a small ovoid and well-circumscribed low signal area (suggestive of the nidus) on the juxta-cortical aspect of the anterior medial aspect of the tibial plateau in the PD sequence. There is extensive surrounding marrow edema.
Case Discussion
The lesion was characterized as an osteoid osteoma after a histopathological report.
Osteoid osteomas are benign tumors. They usually have a typical radiographic appearance of a central lucent nidus with surrounding sclerosis. Intra- and juxta-articular osteoid osteomas, however, may not have the usual radiographic features. In this case, the typical surrounding sclerosis was not present, difficulting the initial diagnosis.
Case contributed by: Dr Marcelo Bragança and Dr Flávia Costa
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