Osteoid osteoma in the differential diagnosis of persistent joint pain.

We report 20 cases (13 male and 7 female), mean age 21 years) of juxta-articular osteoid osteoma. The distribution of affected joints was as follows: hip joint (7 cases), knee joint (2 cases), ankle joint (2 cases); iliosacral joint (2 cases), lumbar spine (2 cases), carpus (2 cases), shoulder (1 case), second metacarpal (MCP; 1 case) and first metatarsal (MTP; 1 case). The duration between the onset of symptoms and diagnosis varied from 8 months to approximately 4 years. In juxta-articular osteoid osteoma, the clinical picture and the radiographic findings are often atypical, and this may lead to misdiagnosis and delayed definitive treatment. In young patients with persistent undiagnosed pain, the possibility of an osteoid osteoma should be considered. When the clinical picture is suggestive but radiological findings are negative, we must proceed to further investigation with bone scintigraphy and computed tomography. These examinations should be repeated 1 year after the onset of symptoms because initially negative findings may become positive at a later date. When the diagnosis of an osteoid osteoma is confirmed, surgical excision leads to complete relief of the symptoms.