Ted Wagner Case of the Month  

"When you hear hoofbeats, think horses, not zebras" is one of medicine's most enduring sayings. Dr. Ted Wagner presents a true "zebra" back pain case.

Authors: Drs. Ted Wagner and Courtney O'Donnell, PGY-3 (not pictured)

Patient History

Zebra COTM Figure 1

Figure 1

A 12-year-old athletic farm boy presents with low back pain for four months. The onset is vague and is not related to any incident of trauma.

He characterizes the pain as an aching that extends onto his buttocks and tightness in his posterior thighs. He feels very "stiff," and his father notes he leans to the left. He has nighttime aching discomfort and gets some relief with ibuprofen. The patient has had no systemic illness, weight loss or fever.


Zebra COTM Figure 2

Figure 2

Patient stands with a slight tilt to the left. When bending forward he rotates to the left and his return to standing is not a smooth process. He has hamstring tightness when bending forward. There is no point tenderness, but asymmetrical tension of the lumbar musculature. The neurologic exam is normal.


Nonrotated mild scoliosis to the left. Lateral X-ray reveals a grade 1 spondylolisthesis.


Confirmed the L5/S1 spondylolisthesis and a questionable L2 lesion in posterior element on the left side.

Bone Scan

Moderately positive at L2 on the left side.

CT Scan

Confirmed a left L2 posterior lamina and pedicle lesion.


Open biopsy of the left L2 lamina and pedicle. Under the same anesthesia, had an L5/S1 fusion with instrumentation.


Nondiagnostic "fibrous tissue."

Post-Op Three Months

Same pain pattern, the same scoliosis, and the same dysrhythmic motion of the lumbar spine.

Surgery #2 (Four Months Later)

Resection of hemilamina and portion of the left pedicle.


"Osteoblastoma," "plump osteoblasts," "osteoplastic giant cells" surrounded by "sclerotic reactive bone."


Zebra COTM Figure 3

Figure 3

Adolescent low back pain is common. As a first-time complaint, 90% will resolve in six weeks. 70% of persistent low back pain lasting more than six weeks may have a stress facture of the pars interarticularis (spondylosis). The less common diagnoses would include infection, disc herniation, spondylolisthesis and tumors. Lab test and a magnetic resonance imaging (MRI) are appropriate for a child with this clinical presentation. In this case, two distinct diagnoses were made and treated, but the primary cause of his low back pain was the inflammatory lesion at L2.

An osteoid osteoma and osteoblastoma are benign neoplasms, and the difference is a matter of size.


These tumor cases may appear in any bone, 70% are in the lower extremities, and the common age is 4 to 25 years old. 7% occur in the spine, and most in the lumbar spine. Classically, they present with low back pain, scoliosis (stiffness in the spine) and night pain. They often respond to anti-inflammatories (aspirin or other).

In this case, the patient's suspected diagnosis included the obvious spondylolisthesis and questionable lesion of L2. The biopsy was unsuccessful because the biopsy tissue did not include the nidus (center) of the lesion.

The one-year outcome after the second surgery, which was the complete resection, is complete resolution of the symptoms and restoration of his normal rhythmic range of motion of his lumbar spine.

Although the surgical excision has been the established especially in the spine, the alternative and effective treatment of many osteoid osteomas is with radiofrequency ablation performed by an interventional radiologist. Both treatments approach a 95% cure. It is important to realize that if no treatment is rendered, the symptoms will eventually fade away after four or five years.

Points to Be Made

  1. Be suspicious of an adolescent with everyday back pain and with night pain with a disturbed posture for more than six weeks.
  2. The obvious spondylolisthesis may not be the primary diagnosis.

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