evaluation of athletic hip pain routinely includes radiographs and magnetic resonance imaging ( mri ) . computed tomography ( ct ) is applied at some centers and in certain clinical scenarios . although mri (  arthrogram ) alone can clearly define changes to labrum or cartilage , osseous pathology may be underappreciated . we present the case of an unrecognized osteoid osteoma in a patient with femoral acetabular impingement ( fai ) , cam morphology , and labral injury to emphasize the need to maintain a high index of clinical suspicion for this atypical cause of hip pain . a 19-year - old male soccer player presented with hip pain unresponsive to non - steroidal anti - inflammatory drugs ( nsaids ) and physical therapy . range of motion demonstrated 10 loss of internal rotation and muscle weakness ( 4+/5 hip flexion ) was present . radiographs revealed cam morphology (  angle  =  74 ) with slight acetabular retroversion ( + cranial crossover sign ) ( fig . ( c ) ct of patient s right hip revealing osteoid osteoma at the lesser trochanter . ( d , e ) right hip ct scan in prone position with needle and radiofrequency ablation system at level of the osteoid osteoma . ( c ) ct of patient s right hip revealing osteoid osteoma at the lesser trochanter . ( d , e ) right hip ct scan in prone position with needle and radiofrequency ablation system at level of the osteoid osteoma . incidentally noted was the atypical appearance of the lesser trochanter attributed to lesser trochanter apophysitis . mri arthrogram confirmed labral tear , partial thickness chondral injury with mild iliopsoas tendonitis with bone marrow edema at the lesser trochanter . one year later the patient returned with buttock pain but denied anterior hip or groin pain . repeat radiographs and mri arthrogram revealed well healed labrum and no evidence of heterotopic ossification . ct with 3d reconstruction confirmed extent of bony resection but also clearly defined the osteoid osteoma nidus at the lesser trochanter ( fig . salicylic acid failed to relieve pain and the patient was referred for radiofrequency ablation . under ct guidance , via a posterolateral approach , a 10-gauge bone biopsy needle was advanced to the nidus of the osteoid osteoma and through the reactive bone . radiofrequency ablation was performed at the proximal and distal termini of the nidus and surrounding periosteum using a dfine , inc . post - procedure recovery was uneventful and at 3 months the patient returned to all activities denying further hip pain . our case emphasizes the value of advanced imaging in the setting of any incompletely defined bony changes of the proximal femur or acetabulum . due to limitations of radiographs and mri , bony changes were inaccurately attributed to apophysitis versus osteoid osteoma . we also draw attention to the complete lack of response to nsaids for the entirety of this patient s treatment . recent literature has shown that clinical response to nsaids in osteoid osteoma may be overstated . the lack of response certainly does not exclude osteoid osteoma as the cause of pain [ 3 , 4 ] . the authors report no funding or external sponsors relevant in the authorship and publication of this clinical vignette formal conflict of interest statement : the authors report no conflict of interest or disclosures relevant in the authorship and publication of this clinical vignette .