A rare pathology in the differential diagnosis of joint pain: Intraarticular osteoid osteoma

Osteoid osteoma (OO) is a benign osteoblastic tumor of bone that usually affects children and young adults. They are usually located on the metaphysis or diaphysis of long bones. Their clinical, anamnesis and radiological findings are typical. Intra-articular OO however, has different properties due to its placement within joints. Sclerosis around the lesion is either minimal or non-existent, but synovitis can be seen in the joint. For this reason, they are usually diagnosed later. In this case series, we diagnosed three cases (2 ankles and 1 hip joint) that were diagnosed with osteochondral lesions previously and had chronic pain that did not respond to several treatments in different centers with intra-articular OO and treated them with radiofrequency ablation using computerized tomography. Knowing the radiological properties of intra-articular OO and being aware of this condition during the differential diagnosis of joint pain cases will be useful to diagnose this rare pathology.