Osteoid osteoma of the femoral neck stimulating an inflammatory synovitis.

The case report presents a nine-year-old child with an osteoid osteoma of the femoral neck, simulating an inflammatory synovitis. Osteoid osteoma is a common benign bone tumor. However, when intracapsular lesions occur they may pose a diagnostic challenge. Nonspecific clinical signs and symptoms, such as inflammatory synovitis, joint effusion, and soft tissue swelling, may pose a problem in diagnosis and treatment. The delay in diagnosis can range from six months to two years. When the hip is involved, the patient may have nonspecific pain, limp, restricted motion, and thigh atrophy. An accurate diagnosis may be difficult to elicit, requiring detailed history and physical examination and culminating in the use of computed tomography.