[Neurological manifestations of an osteoid osteoma located on the femoral neck in an 8-year-old boy].

We report the case of an 8-year-old boy, suffering from nocturnal pain localized on the left groin and presenting as a limp over several months. Examination revealed diminished strength of the left leg, atrophy of the thigh and calf, and a diminished deep tendon reflex. The pain could be intense and the patient had found an analgesic position by pushing on his groin or by flexing his thigh on the pelvis. He could no longer run. He was unsuccessfully treated with carbamazepine and gabapentin. His evaluation included a negative abdominal ultrasound study and a normal spine and cerebral MRI. Electromyography was unremarkable. He finally underwent an MRI of the pelvis that revealed a hyperintense T2 signal of the left femoral neck; CT confirmed the diagnosis of osteoid osteoma. Radiofrequency ablation of the lesion was performed. His clinical state dramatically improved after the procedure. His walk is normal, without any limping. Deep tendon reflexes are normal, and he only presents residual pain. Physicians should be aware that osteoid osteoma may take the form of a slowly evolving neuropathy. We review the literature on this underestimated condition.