[An adolescent man with pain at night in his lower right leg].

A 22-year-old man is referred to the orthopaedic surgeon. He has pain, mostly at night, in his proximal right tibia that greatly reduces with NSAIDs. The CT scan shows a focal lucent zone, called a nidus, in the tibia cortex, surrounded by reactive, sclerotic bone. This is typical for an osteoid osteoma, a benign bone tumour.