[Intra-articular osteoid osteoma: a rare cause of coxitis]

Osteoid-osteoma is a frequent benign tumor of the bone. In cases with peri- or intraarticular localisation symptoms suggestive of arthritis may occur. We report on a 25-year-old patient with a painful hip during exercise as well as in the night. Conventional radiographs were unremarkable. However, ultrasound and computertomography revealed joint effusion of the hip. Scintigraphic and tomographic findings were compatible with an osteoid osteoma. Histology of the surgically removed tumor confirmed this diagnosis. Moreover, a lympho-follicular synovitis was found.