Intra-articular osteoid osteoma as a cause of chronic ankle pain

Patients with intra-articular osteoid osteomas present with pain, swelling, and limited joint motion. Delays in diagnosis are common because plain radiographs can appear normal. Synovial biopsy reveals nonspecific lymphofollicular proliferation that can be confused with inflammatory arthropathies. Diagnosis is often delayed and in cases where the delays are significant, joint arthrosis can supervene, further complicating the clinical picture. BS and CT are helpful in diagnosing and localizing the lesion.