Rapid development of severe osteoarthritis associated with osteoid osteomain a young girl

In a 14-year-old girl with a 5 month history of left sided thigh pain, X-ra ys demonstrating osteoarthritis and a bone scintigraphy showing increased f ocal uptake in the femoral neck led to the diagnosis of an osteoid osteoma. The protruberant bone at the femoral neck was removed en-bloc and the diag nosis histologically confirmed. The synovium was extensively infiltrated wi th lymphocytes. Postoperatively the girl experienced neither the expected p ain relief nor improvement of her hip function over the next 4 months. MRI and CT results indicated development of a severe osteoarthritis even though no residual lesion could be found.