Unrecognized osteoid osteoma of the proximal femur with associated cam impingement.

Femoro-acetabular impingement is a common cause of hip pain in young athletes. Evaluation typically includes radiographs and magnetic resonance imaging. It is important to appreciate uncommon diagnoses and the role of complimentary imaging. This clinical vignette emphasizes the need complete imaging with CT in select case of atypical hip pain. We present a 19-year old soccer player who underwent seemingly successful arthroscopic FAI surgery but returned with pain. Computed tomography (CT) revealed osteoid osteoma of the lesser trochanter. The lesion was successfully treated with percutaneous CT guided radiofrequency ablation.