Volume 4, Case 15
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaiʻi John A. Burns School of Medicine
This is a 7-year old male who is seen in the acute care clinic with a history of recurrent pain in his left thigh for three months. He has seen his primary care physician on two occasions. Initially, this pain would awaken him at night, but it would subside on its own. When he saw his primary care physician for this, he was told it was growing pains. He then began to complain of pain during the day. He was given acetaminophen without relief. His primary care physician prescribed ibuprofen and this helped to relieve the pain. However, the pain continued to worsen and his parents decided to bring him to an acute care clinic after he complained of the pain all day in school. There is no history of fever, trauma, or pains in other bones or joints.
Exam: VS T37.0 (oral), P88, R28, BP 100/50. He is of average height and weight. He is able to ambulate well with a slight non-specific limp to his gait. He complains of some pain while walking. He continues to complain of pain while he is sitting at rest. He localizes his pain by pointing to his proximal thigh. There is no position of comfort that completely relieves him of pain. His left hip has a diminished range of motion due to moderate tenderness. There is some tenderness on palpation to the hip joint, but it is not severe. There is no tenderness over his mid and distal femur. His heart, lungs, and abdomen are unremarkable. His other joints are unremarkable. There is no lymphadenopathy.
Radiographs of his hips are obtained.
View hip radiographs.
AP (upper image) and frog (lower image) views are shown here. His findings are best seen on the AP view. His left hip (right side of the image) shows some demineralization of the femoral head. The joint space is slightly widened. There is slight thickening of the medial cortex of the femoral neck (the calcar). There is a faint oval lucency within the femoral neck. The radiologist suspects an osteoid osteoma.
View pointers on hip radiographs.
The white outlined arrow points to the lucency within the femoral neck (the suspected osteoid osteoma). The gray outlined arrow points to the thickened cortex along the calcar. The vertical white lines measure the width of the hip joint space. The "tear drop" distance measures the medial margin of the inferior aspect of the acetabulum to the adjacent femoral head. This distance is wider in the left hip compared to the right hip.
An ultrasound of the hips is obtained.
View hip ultrasound.
The image on the left is the right hip. The image on the right is the left hip. The letter "F" marks the proximal femur. The femoral head is to the left of the image. The number "1" measures the width of the joint space in the right hip. The number "2" measures the width of the joint space in the left hip. The ultrasound confirms the presence of a small left hip effusion.
A CT scan is ordered.
View CT scan.
This cut from the CT study is through the lucency noted in the femoral neck on the plain radiographs. The arrow points to the osteoid osteoma.
Our patient's symptoms improve with aspirin. Acetaminophen and ibuprofen do not result in significant pain relief. His symptoms later worsen and standard doses of aspirin no longer control the pain as well. The lesion is surgically resected. Following surgery, his symptoms resolve.
Osteoid osteoma is a benign bone tumor most commonly found in the 5 to 25 year age group. The male to female ratio is 3 to 1. The femur and tibia account for 50% of cases. Other common sites include the hands, feet, and spine.
Patients with spinal osteoid osteoma are difficult to diagnose since it does not usually reveal itself on plain radiographs. These patients usually present with painful scoliosis. Osteoid osteoma of the spine should be considered in young patients with painful scoliosis.
The pain of osteoid osteoma is described as unrelenting and sharp, worse at night. Classically, the pain is relieved by aspirin. The source of the pain is unclear. Prostaglandins are suspected, however, non-steroidal anti-inflammatory agents such as ibuprofen do not always relieve the pain as well as aspirin.
The classic radiographic features of osteoid osteoma are a well-defined, round (or oval) radiolucent lesion with a surrounding radiodense zone (reactive sclerosis).
View classic appearance.
Both views show this classic appearance of an osteoid osteoma in the proximal left femur (central lucency with surrounding sclerosis). While this appearance is classic, osteoid osteoma may have a subtle appearance as noted in the first set of radiographs. Other common radiographic appearances of osteoid osteoma include dense bone alone or a lucency alone.
It is common for osteoid osteomas to show osteopenia and cortical thickening in adjacent bone due to reactive sclerosis (as seen in the first patient). Intra-articular osteoid osteomas may result in joint effusions.
It is suspected that osteoid osteoma (and its pain) may resolve spontaneously. This is thought to be due to spontaneous involution of the painful lesion. In some instances, aspirin can be used to control the pain until spontaneous involution occurs. However, in most instances, the pain intensity worsens and surgical resection is chosen.
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