Proximal femoral intra-capsular osteoid osteoma in a 16-year-old male with epiphyseal periostitis contributing to Cam-type deformity relating to femoro-acetabular impingement

摘要

Osteoid Osteoma was originally described in 1935 by Jaffe [1] , and is one of the most common benign bone tumours [2] , accounting for the majority of bone tumours in those under 25 years of age [3]. These are benign, osteoid-producing lesions for which nocturnal pain is markedly reduced or relieved by anti-inflammatories, typically salicy-lates. Males are affected more than females, at approximately a 3:1 ratio [4]. Typical imaging features include a central osteolytic nidus surrounded by sclerosis and adjacent periosteal reaction [2, 5, 6]. The most common location is the proximal femur [7], and the degree of bone edema can be variable. Rarely are osteoid osteomas intra-capsular, although they may then result in minimal periosteal reaction, marked synovitis or mimic other aetiologies, benign or malignant.