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A 16-year-old female with progressive back pain and right leg numbness
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An otherwise healthy 16-year-old female patient was referred to the pediatric orthopedic clinic with a 1-year history of progressive left paraspinal thoracolumbar back pain and right lower extremity paresthesias. Initially, the paresthesias started on the dorsum and lateral aspect of the right foot with eventual progression more proximally over the lateral aspect of the leg and hip. The patient denied any history of trauma or an inciting event, as well as any constitutional symptoms. She maintained normal bowel and bladder function. The use of NSAIDs provided moderate back pain relief, but did not affect the paresthesias. The patient had not undergone any prior treatment. She initially presented to her general pediatrician, who obtained an MRI of the thoracic and lumbar spines that demonstrated multifocal osseous lesions that involved the thoracic and lumbar spines, as well as multiple rib lesions, which raised the concern for malignancy (Figure 1).
The patient had no significant past medical or surgical history. She maintained an active lifestyle, which included competitive softball and basketball, both of which she was forced to stop following progression of her back pain.
Images: Eno J-JT
On exam, the patient was able to heel-and-toe walk without difficulty and had full strength of all her extremities. She had moderate left paraspinal tenderness at the thoracolumbar junction without significant spinal curvature or asymmetry. She had decreased sensation over the dorsal and lateral aspects of the right foot extending proximally over the lateral lower leg and thigh. Straight-leg and contralateral straight-leg raise tests were negative. Normal abdominal and lower extremity reflexes were present, and the lower extremities were warm and well-perfused.
After evaluation, plain films and a CT of the thoracic and lumbar spine were obtained (Figures 2 and 3).
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Melorheostosis
Melorheostosis is a poorly understood bony dysplasia that may present with findings in the extremities and with even more subtle findings when the axial skeleton is involved. Classically, soft tissue contractures, bone spurring and pain at the site of osseous lesions characterize the disorder. However, there is a broader range of signs and symptoms which can include joint swelling, progressive loss of motion, overlying skin changes including pigmentation, induration and edema, and soft tissue masses. Regarding melorheostosis of the spine, the incidence is low and patients are often asymptomatic. When symptoms do present, they usually manifest as back pain with neurological deficits.
The etiology of melorheostosis is unknown. Observations have characterized the disease spectrum to include vascular insufficiency to failure of intramembranous and endochondral ossification. Further theories propose an underlying connective tissue disorder or possible embryologic damage. Basic science research has identified loss of function mutation of a nuclear membrane protein as a potential source of the problem; however this mutation is not found in all cases, which suggests a true genetic cause has not yet been identified.
Image: Hazard FK
More relevant to the clinician is the characteristic radiographic features of melorheostosis. Asymmetric bands of sclerosis in a linear pattern, which are classically described as “melted wax appearance,” are characteristic of the disorder. Findings are often unilateral and the cortex is almost always involved. More infrequently, cancellous involvement can be seen, particularly in the pediatric population. Long bones are common sites of occurrence. Spine involvement is often asymptomatic, but it can progress to stenosis that results in significant pain and neurologic deficits.
Histology and treatment
The histopathologic appearance of melorheostosis is dense cortical bone without cellular abnormalities (Figure 4).
Treatment for melorheostosis is symptom-based. Treatment guidelines are challenging to create because patients have a broad range of symptoms and may develop significant deformities that eventually require surgery. Goals of treatment include pain relief and preservation or improvement in function.
Surgery is indicated for extremity contractures and limb length inequalities and may include soft tissue procedures (release, tendon lengthening, etc.), as well as bony correction (osteotomy, epiphysiodesis or fusion). Patients must be counseled that surgery for deformity correction carries a high risk of recurrence. Surgery for spinal involvement includes decompression and fusion procedures. Literature for melorheostosis of the spine is limited to case reports. Although it is rare, a standard work up for chronic back pain, including plain films and advanced imaging of the spine, will likely yield the correct diagnosis.
Outcome
With examination and imaging concerning melorheostosis that caused spinal stenosis at T9-10, the patient underwent a decompressive right hemilaminectomy and biopsy. Pathology confirmed the diagnosis of melorheostosis. At the 6-week follow-up, the patient reported complete resolution of her right lower extremity paresthesias and back pain. She maintained full strength in all extremities and is undergoing physical therapy in anticipation of return to full activities.
- References:
- Campbell CJ, et al. J Bone Joint Surg Am. 1968; 50:1281-1304.
- Freyschmidt J. Eur Radiol. 2001;doi:10.1007/s003300000562.
- Jain VK, et al. Orthopedics. 2009;doi:10.3928/01477447-20090527-20.
- For more information:
- Jonathan-James T. Eno, MD, can be reached at 450 Broadway St., Redwood City, CA 94065; email: jeno@stanford.edu.
- Florette K. Hazard, MD, can be reached at Stanford University School of Medicine, 300 Pasteur Dr., Stanford, CA 94305; email: fkgray@stanford.edu.
- Lawrence A. Rinsky, MD, can be reached at Packard Children’s Orthopaedic Center, 730 Welch Rd., Palo Alto, CA 94305; email: lrinsky@stanford.edu.
- Chason Ziino, MD, can be reached at 450 Broadway St., Redwood City, CA 94065; email: chason@stanford.edu.
Disclosures: Eno, Hazard, Rinsky and Ziino report no relevant financial disclosures.