Osteoid osteoma with a multicentric nidus: a case report and review of the literature.

To date, 23 cases with osteoid osteoma (OO) including multiple nidi in single bone have been reported in the world literature. A case report of an 18-year-old boy with an OO on his left femoral neck, which contained double nidi is presented. Plain radiography, computed tomography (CT) and magnetic resonance imaging (MRI) of the proximal femur showed OO with a multicentric nidus. Bone scintigraphy demonstrated increased activity in the left femoral neck region. The tumor was removed with curettage and shaving using lateral approach. The patient was asymptomatic for 5 years after surgery.