An aneurysmal bone cyst (ABC) of the spine is a rare, non-cancerous, blood-filled bone lesion that can expand rapidly, weaken the vertebral column, and compress the spinal cord. Although benign, ABCs can be locally destructive. In the spine, that local growth can turn what initially seems like routine back pain into a serious neurological problem.
Key Takeaways
- Aneurysmal bone cysts (ABCs) are benign, not malignant, vascular bone lesions. They do not metastasize to other organs, but they can expand locally, weaken the affected bone, and, in the spine, compress the spinal cord.[1][4]
- Imaging may show an expansile, lytic, ‘soap-bubble‘ lesion and fluid-fluid levels on MRI. Biopsy or surgical pathology is needed to distinguish an ABC from malignant lesions such as telangiectatic osteosarcoma.[2][3]
- Treatment may involve preoperative embolization, surgical resection, spinal stabilization, or, in selected cases, less invasive approaches. Neurological deficits can improve after decompression, and outcomes following treatment are generally favorable.[2][3][6]
Not Cancer, But Not Harmless
An aneurysmal bone cyst (ABC) is not a cancer.[4] It does not spread to distant organs or have the metastatic potential associated with malignant bone tumors. That distinction is important, but a benign diagnosis does not mean the lesion can be ignored. An ABC can enlarge within the bone, thin the surrounding cortex, and, when it develops in the spine, compress the spinal cord or nerve roots.[1][4]
Untreated lesions can lead to pathologic fracture or neurological compromise. For patients and families, the message is straightforward: the lesion is not malignant, but it can still require urgent treatment when it threatens the stability of the spine or the structures within the spinal canal.
What is an Aneurysmal Bone Cyst?
An ABC consists of blood-filled spaces separated by fibrous septa containing osteoclast-type giant cells.[2] It occurs most often during the second decade of life. Although ABCs can develop in any bone, common sites include the long bones of the arms and legs, the pelvis, and the spine.[1][4] Spinal ABCs are less common than ABCs involving the long bones, but their location creates an additional concern because an expanding lesion can encroach on the vertebral canal.
Two categories are recognized. Primary ABCs arise independently and are associated with a rearrangement involving the USP6 gene. Secondary ABCs develop in association with another underlying lesion, including giant cell tumor, chondroblastoma, or osteoblastoma. These lesions can have the same histologic appearance without the same genetic alteration.[2]
Why the Spine Is Different
In the long bones, an expanding ABC commonly causes pain, swelling, or pathologic fracture. In the spine, the lesion can also threaten the spinal cord. Spinal ABCs often originate in the posterior elements, particularly the pedicle, and can extend into the vertebral body and, in some cases, the spinal canal.[2] A case series published in the Asian Journal of Neurosurgery described the “winking owl” sign on plain radiographs. The sign results from erosion of a vertebral pedicle, causing it to disappear on the anteroposterior image, and can provide an early radiographic clue.[2]
Symptoms may develop gradually or appear suddenly. In a case reported in Translational Cancer Research, a 12-year-old girl with no preceding back symptoms developed acute bilateral leg weakness and sensory loss within minutes of a minor fall. Evaluation showed that a previously silent thoracic ABC had narrowed the spinal canal and compressed the cord.[3] This case shows how a spinal ABC can remain clinically silent until the lesion has produced substantial spinal canal narrowing.
Recognizing the Symptoms
Early symptoms can resemble more common musculoskeletal conditions, which may delay diagnosis. Patients may present with localized, progressively worsening back or neck pain, stiffness, or swelling near the affected spinal level.[2][3] When the lesion involves neural structures, symptoms may include numbness, radiating pain, or weakness affecting the arms or legs. Bowel or bladder dysfunction can indicate more advanced spinal cord or cauda equina involvement and requires urgent evaluation.
Diagnostic Approach
Plain radiographs may show an expansile, lytic lesion with thinning of the cortical margin, often described as having a ‘soap-bubble’ appearance.[1][4] CT provides a more detailed assessment of the bony architecture and the extent of vertebral involvement. MRI is particularly useful because it can demonstrate the multiloculated lesion and the fluid-fluid levels produced by blood products of different densities within the cyst.[2][3]
Imaging findings alone, however, are not sufficient to establish the diagnosis. Giant cell tumor and telangiectatic osteosarcoma can produce similar radiographic findings. Tissue diagnosis, obtained through needle or open biopsy or from the surgical specimen, is therefore important to confirm an ABC and exclude malignancy.[2][3]
Tumor Control and Neurological Risk
Treatment of a spinal ABC requires consideration of both recurrence risk and the anatomical risks associated with operating near the spinal cord and nerve roots. For patients without neurological compromise, selective arterial embolization or intralesional treatment with agents such as calcitonin and corticosteroids has been described.[2] These approaches can promote sclerosis and bone remodeling but may require months or years to achieve control.
When neurological deficits or spinal instability are present, surgical decompression is generally required. Preoperative embolization is frequently performed to reduce blood loss by blocking the vessels supplying the highly vascular lesion before surgery.[2][3] Complete removal of the cyst wall and abnormal hypervascular tissue provides the best chance of durable local control. In spinal ABCs, incomplete curettage has been associated with higher recurrence rates than complete resection.[2] When removal of the lesion compromises spinal stability, instrumented fusion with pedicle screws and rods may be required to maintain the structural integrity of the spinal column.[2][3]
A Recent Case Illustrates the Stakes
The potential neurological consequences of a spinal ABC were illustrated in a case reported by Cedars-Sinai in August 2026 involving a teenage patient, Ryan Soliz. His back pain was initially attributed to a musculoskeletal strain, but the symptoms progressed over several months and eventually affected his ability to walk. Imaging revealed a large lesion occupying a substantial portion of the spinal canal. Biopsy confirmed an aneurysmal bone cyst. According to the treating team, the lesion’s benign classification did not make it less dangerous because it obstructed spinal fluid flow and compressed the spinal cord.[5]
Soliz subsequently developed worsening neurological symptoms, including loss of sensation in his legs. The treatment team expedited care, and interventional neuroradiology performed embolization of the tumor’s blood supply before a five-hour surgical resection. The procedure relieved the spinal cord compression and preserved his ability to walk.[5] Several months later, a recurrence was identified and treated with repeat embolization, allowing him to avoid a second operation.[5]
The case underscores the importance of coordinating imaging, interventional radiology, surgery, and postoperative care when a spinal ABC threatens neurological function.
Recovery, Recurrence, and Follow-Up
The prognosis after treatment of an aneurysmal bone cyst, including spinal disease, is generally favorable.[6] Neurological deficits can improve after decompression, and substantial recovery has been reported even in patients who present with significant neurological impairment. Recurrence remains an important concern. Reported recurrence rates for spinal ABCs after treatment range from approximately 10% to 25%, depending on factors such as the completeness of resection and the treatment approach.[2]
For that reason, patients generally require continued radiographic follow-up, often with serial imaging over one or more years. In children and adolescents who are still growing, follow-up may continue until skeletal maturity.[2]
What’s Next
Because spinal ABCs are rare, treatment decisions are not based on large randomized clinical trials. Much of the available evidence comes from case reports and case series.[2][3] The relative roles of embolization, sclerotherapy, and surgery in neurologically intact patients with unstable or high-risk lesions remain undefined. Comparative data specific to spinal ABCs remain limited.[2][3] Medical approaches targeting osteoclast activity, including denosumab*, have also been reported in individual cases, but controlled studies have not established these treatments for spinal ABCs.[2]
The available evidence therefore supports an individualized approach based on lesion location and extent, spinal stability, neurological involvement, and treatment-related risks.
Note
Denosumab was originally developed and manufactured by Amgen under the brand names Prolia® and Xgeva®, though several pharmaceutical companies now produce approved biosimilar versions.
References
[1] Cleveland Clinic. Aneurysmal Bone Cyst. Patient education resource. Online. Last accessed on September 7, 2026
[2] Cugati G, Pande A, Jain PK, Symss NP, Ramamurthi R, Vasudevan CM. Aneurysmal bone cyst of the lumbar spine. Asian J Neurosurg. 2015 Jul-Sep;10(3):216-8. doi: 10.4103/1793-5482.161179. PMID: 26396610; PMCID: PMC4553735.
[3] Gu Y, Chen X, Zhou L, Liu W. An aneurysmal bone cyst ruptured and compressed the spinal cord: a case report. Transl Cancer Res. 2020 Aug;9(8):5008-5014. doi: 10.21037/tcr-20-1124. PMID: 35117863; PMCID: PMC8797431.
[4] American Academy of Orthopaedic Surgeons. Aneurysmal Bone Cyst. OrthoInfo patient education resource. Online. Last accessed on September 7, 2026
[5] Sandoval K. Rare Spinal Tumor Threatened Teen’s Ability to Walk. Cedars-Sinai. August 24, 2026. Online. Last accessed on September 7, 2026
[6] Ann & Robert H. Lurie Children’s Hospital of Chicago. Aneurysmal Bone Cysts (ABCs) in Children. Neurointerventional Radiology Program patient education resource. Online. Last accessed on September 7, 2026
This article is intended for informational purposes for healthcare professionals and does not constitute medical advice. Clinical descriptions of individual patient cases are drawn from published institutional accounts; treatment decisions for any individual patient should be made in consultation with a qualified spine oncology or neurosurgical team.
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