Osteoid osteoma is a benign lesion that accounts for approximately 10% of benign bone tumors. It occurs predominantly in children and young adults between 10 and 25, affecting males twice as often as females. The clinical presentation typically consists of pain, which is often worst at night, increased skin temperature, sweating, and tenderness in the affected region. Pain is completely relieved by salicylates in many cases.
Predilection sites are proximal femur, and diaphysis of long bones, which account for more than half of all cases, and less often foot and the posterior elements of the spine (1). Osteoid osteomas are usually detected on radiographs, typically showing a radiolucent nidus surrounded by sclerosis in the cortex of the bone. If an osteoid osteoma is suspected and radiographs are negative, skeletal scintigraphy is especially useful with a sensitivity of 100% (2). Radionuclide angiography and tissue-phase imaging often, but not always, show prominent tracer delivery and early localization. On skeletal-phase images a well-localized, focal tracer uptake is typically noted (3). Characteristic is a cloud of diffuse increase of radiotracer around the prominent focus, which is better seen on images obtained with pinhole magnification technique (4). In complicated cases computed tomography might be helpful to visualize the nidus. Scintigraphy also is contributory for treatment of patients with osteoid osteoma by ensuring complete removal of the lesion. This can be achieved either by imaging the specimen that should demonstrate a normal margin of bone around the lesion or intraoperatively with a mobile gamma camera, demonstrating that no residual activity suggestive of osteoid osteoma tissue is left (5).
Predilection sites are proximal femur, and diaphysis of long bones, which account for more than half of all cases, and less often foot and the posterior elements of the spine (1). Osteoid osteomas are usually detected on radiographs, typically showing a radiolucent nidus surrounded by sclerosis in the cortex of the bone. If an osteoid osteoma is suspected and radiographs are negative, skeletal scintigraphy is especially useful with a sensitivity of 100% (2). Radionuclide angiography and tissue-phase imaging often, but not always, show prominent tracer delivery and early localization. On skeletal-phase images a well-localized, focal tracer uptake is typically noted (3). Characteristic is a cloud of diffuse increase of radiotracer around the prominent focus, which is better seen on images obtained with pinhole magnification technique (4). In complicated cases computed tomography might be helpful to visualize the nidus. Scintigraphy also is contributory for treatment of patients with osteoid osteoma by ensuring complete removal of the lesion. This can be achieved either by imaging the specimen that should demonstrate a normal margin of bone around the lesion or intraoperatively with a mobile gamma camera, demonstrating that no residual activity suggestive of osteoid osteoma tissue is left (5).
D/D: Osteomyelitis
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