Radiology Cases in Pediatric Emergency Medicine
Volume 4, Case 15
Loren G. Yamamoto, MD, MPH
Kapiolani Medical Center For Women And Children
University of Hawaii 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
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
The classic radiographic features of osteoid
osteoma are a well-defined, round (or oval) radiolucent
lesion with a surrounding radiodense zone (reactive
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
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
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.
Springfield DS. Bone and Soft Tissue Tumors. In:
Morrissy RT (ed). Lovell and Winter's Pediatric
Orthopaedics, third edition. Philadelphia, J.B. Lippincott
Co., 1990, pp. 323-363.
Bisset GS. Case 26: Osteoid Osteoma. In: Siegel
MJ, Bisset GS, Cleveland RH, et al. Pediatric Disease
(Fourth Series) Test and Syllabus. Reston, Virginia,
American College of Radiology, 1993, 691-719.
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Web Page Author:
Loren Yamamoto, MD, MPH
Associate Professor of Pediatrics
University of Hawaii John A. Burns School of Medicine