Aneurysmal Bone Cyst Presenting with Neurological Deficit: Two Cases Reports and Review of the Literature

Abstract

Aneurysmal bone cysts are rare, benign, hypervascular lesions, locally destructive due to their progressive growth. The severity of symptoms depends on the degree of associated spinal cord injury. The surgical approach is the main treatment method and aims at complete tumor resection with reconstruction and/or stabilization of the spine. The goal of this study is to present the authors' experience with surgical treatment of aneurysmal bone cysts of the thoracolumbar spine in the pediatric population and describe the treatment in the context of literature. Two patients of the authors and reports in the literature were identified and analyzed. A 16-year-old female presented with acute spinal cord syndrome classified as ASIA A due to thoracic cord compression. The second patient is an 8-year-old male admitted with left leg weakness due to compression of lumbar roots. Both patients underwent complete tumor resection with corpectomy, reconstruction of the anterior spine with body cage, and stabilization of the posterior spine with pedicular screws. After 6 months of surgery, they evolved with significant improvement in motor strength. Even at severe clinical presentation, the patient with an aneurysmal bone cyst may improve neurological deficits if treated in a timely manner, with tumor resection, spinal cord and/or nerve decompression, spinal reconstruction, and postoperative rehabilitation.

 

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Resumo

Os cistos ósseos aneurismáticos são lesões raras, benignas e hipervasculares, localmente destrutivas devido ao seu crescimento progressivo. A gravidade dos sintomas depende do grau de lesão da medula espinhal associada. A abordagem cirúrgica é o principal método de tratamento e visa à ressecção completa do tumor com reconstrução e/ou estabilização da coluna vertebral. O objetivo deste estudo é apresentar a experiência dos autores com o tratamento cirúrgico de cistos ósseos aneurismáticos da coluna toracolombar na população pediátrica e descrever o tratamento no contexto da literatura. Dois pacientes dos autores e relatos na literatura foram identificados e analisados. Uma adolescente, de sexo feminino, de 16 anos apresentou síndrome medular aguda classificada como ASIA A devido à compressão da medula torácica. O segundo paciente é uma criança, do sexo masculino, de 8 anos de idade, admitido com fraqueza na perna esquerda devido à compressão das raízes lombares. Ambos os pacientes foram submetidos à ressecção completa do tumor com corpectomia, reconstrução da coluna anterior com body cage e estabilização da coluna posterior com parafusos pediculares. Após 6 meses da cirurgia, evoluíram com melhora significativa da força motora. Mesmo com quadro clínico grave, o paciente com cisto ósseo aneurismático pode melhorar os déficits neurológicos se tratado em tempo hábil, com ressecção do tumor, descompressão da medula espinhal e/ou nervos, reconstrução da coluna e reabilitação pós-operatória.

 

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Keywords

aneurysmal bone cysts - thoracic spine - arthrodesis - spinal cord

Palavras-chave

cistos ósseos aneurismáticos - coluna torácica - artrodese - medula espinhal

Introduction

Aneurysmal bone cysts (ABC) are benign, hypervascular, osteolytic lesions that can cause local destruction, primarily occurring in the metaphysis of long bones and along the spine.[1] [2] They were first described in 1942 by Jaffe and Lichtenstein, and subsequently became known as Jaffe-Lichtenstein Disease.[3]

ABCs are more common in women, with an incidence of 1.4 per 100,000 people and a prevalence of 75 to 90% in individuals under 20 years old (1.05 to 1.26 per 100,000).[1] They predominantly affect the pediatric population, with peak incidence occurring in the second decade of life.[4] ABCs account for 1.4% of bone tumors, compromising approximately 10 to 30% of cases. Common sites include the femur, tibia, pelvis, and, less occasionally, the bones of the hands and feet.[3] [4] Of those affecting the spine, 70% are found in the lumbar region, and 2% are in the cervical segment.[5]

ABCs can be classified as primary or secondary. Primary ABCs, which represent about 70% of cases, are considered neoplastic lesions associated with specific genetic translocation. Secondary ABCs, constituting the remaining 30%, develop due to pre-existing bone lesions, such as hemorrhagic degeneration in giant cell tumors, osteoblastoma, and chondroblastoma.[2] [5]

Patients with spinal ABCs typically present localized pain, as well as neurological deficits depending on the level of spinal involvement. The most common neurological symptoms include changes in sensation, motor strength, and gait. In severe cases, patients may present with plegia.[6] The clinical presentation is influenced by the location and extent of spinal cord or nerve root involvement and the degree of local bone destruction.[7] [8]

In the present study, the authors describe two cases of ABC which were properly treated by surgical management, with tumor resection and reconstruction of the spine.

 

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Cases Descriptions

Case 1

History and Examination

A 16-year-old girl presented with acute paraplegia (ASIA A), sensory level at the T12 level, and neurogenic bladder, following an incident where she experienced a jolt while riding as a passenger on a motorcycle. She was initially admitted to the local hospital and subsequently transferred to a specialized neurosurgical facility.

A comptograph tomography (CT) scan of the spine revealed a collapsed T11 vertebral body, along with an osteolytic lesion involving T10 and T11, accompanied by a kyphotic deformity of the thoracic spine and grade III spondylolisthesis of T11 on T12 ([Figs. 1] and [2]). Magnetic resonance image (MRI) findings showed a heterogeneous, multiloculated mass with thematic content. The mass demonstrated intense septal contrast enhancement, highly suggestive of an aneurysmal bone cyst ([Figs. 3] and [4]). Due to the extent of neurological impairment, the lesion was classified as Enneking stage 3.

Fig. 1 CT of the spine showing a kyphotic deformity of the thoracic spine and grade III spondylolysis of T11 on T12.

Fig. 2 CT of the spine showing a T11 body collapse.

Figs. 3 and 4 MRI show an anomalous, heterogeneous, multiloculated, multiseptated tissue formation, of an inflatable aspect, markedly filled with hematogenic content, characterized by areas by in which liquid-liquid level formation is defined, with intense septal contrast, suggesting ABC enhancement.

 

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Operation

Preoperative embolization was initially proposed but it could not be performed due to the absence of a favorable arterial pedicle. Consequently, the patient underwent complete tumor resection, including total T11 and partial T10 corpectomy. This was followed by anterior spinal reconstruction using a body cage combined with bone graft, and posterior stabilization from T7 to T12 with pedicle screws ([Figs. 5] and [6]). Histopathological evaluation revealed a fibrous bone lesion rich in giant cells with hemorrhagic areas but without significant atypia. Together with the radiological findings, this confirmed the diagnosis of ABC.

Figs. 5 and 6 CT showing total T11 and partial T10 corpectomy, associated with reconstruction of the previous spine with body cage and posterior stabilization from T7 to T12 with pedicle screws.

 

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Postoperative Course

In the immediate postoperative period, the patient evolved without worsening the existing deficit, but still with paraplegia. One week after surgery, the patient began a neurological rehabilitation program. On postoperative day 21, the patient developed a wound infection, which was treated with surgical debridement and intravenous antibiotics (ceftazidime, vancomycin, and meropenem). Around the same time, she experienced extensive thrombosis in the femoro-popliteal-fibular axis, which was managed with full anticoagulation and a vena cava filter. After three months of daily neurological rehabilitation, the patient showed progressive improvement in muscle strength, which began distally in the lower limbs and gradually advanced. At her five-month postoperative follow-up, the patient exhibited a motor strength grade of 4/5 in the lower limbs, with some asymmetry, being slightly weaker on the left side. She was able to walk with the aid of a walker and had regained normal sphincter control. Sensory deficits had almost fully resolved. MRI at 6 months follow-up showed no recurrences.

 

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Case 2

History and Examination

The second patient was an 8-year-old boy who was presented for a neurosurgical evaluation with a seven-month history of lumbago accompanied by sciatica. He reported noticing difficulty walking due to the left leg weakness that had developed three months prior. On physical examination, the patient presented with a muscle strength of 4/5 in the left iliopsoas and, with normal deep tendon reflex. He also exhibited hypoesthesia in the anterior aspect of the left thigh.

A CT scan revealed an osteolytic lesion involving the left posterior element and vertebral body of L3 ([Figs. 7] and [8]). MRI showed a tumor with a low sign on T1-weighted images and a high sign on T2-weighted images. The lesion had multiple internal septations with enhancement and fluid-fluid levels ([Fig. 9]).

Figs. 7 and 8 CT scan showing an osteolytic lesion involving the left posterior element and vertebral body of L3.

Fig. 9 MRI showing a high sign, with multiple internal septations with enhancement and fluid-fluid levels on T2-weighted.

 

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Operation

At first, the patient underwent a percutaneous transpedicular vertebral body biopsy on the left side, which revealed a multiloculated cystic lesion with calcifications, without cytological atypia. The patient continued to experience focal neurological deficit. Considering his neurological deficits, a complete tumor resection, including an L3 corpectomy, followed by anterior spine reconstruction with a body cage and bone graft was performed. The posterior spine was stabilized with pedicular screws from L2 to L4 on the left and right sides.

 

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Postoperative Course

In the postoperative period, the patient demonstrated an improvement in their condition without a worsening of the existing deficit. Physical therapy began three days after surgery, and the patient was discharged on postoperative day five. At a follow-up visit 15 days post-surgery, the patient showed full recovery of muscle strength in the left iliopsoas and quadriceps (5/5), such that the patient was walking without support and without pain complaints. In 1-month follow-up, all sensory deficits had been resolved. MRI at 6 months follow-up showed no recurrences.

 

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Discussion

Aneurysmal bone cysts (ABC) are benign, hypervascularized, osteolytic lesions that are locally destructive and predominantly arise in the metaphysis of the long bones and spine.[1] [2] Clinically, they manifest with pain, which may or may not be accompanied by neurological deficits due to vertebral body fractures or spinal cord and/or root compression. The severity of symptoms depends on the degree of associated spinal cord injury.[6] [9]

In 1986, Enneking classified ABC into three stages of evolution. In the first stage, the lesions are benign, latent, and asymptomatic. In the second stage, they become active and present clinically with pain. The final stage represents aggressive lesions that are often associated with neurological impairment, as seen in the present cases.[10]

Radiological diagnosis of ABC is primarily done through CT and MRI. CT typically reveals an expansive, lytic lesion with thin septa and cortices, suggestive of a cystic lesion. MRI, the preferred modality for detecting neurological compression, epidural extension, and internal septations, frequently demonstrates the “fluid-fluid” pattern, which can be critical for planning surgical resection.[9] [11] [12] These imaging findings are consistent with those observed in our reports.

The definitive diagnosis of ABC is achieved through histopathological analysis, which reveals circumscribed cystic lesions filled with blood and separated by fibrous septa. These septa contain soft fibroblasts, osteoclast-like giant cells, and reactive bone tissue surrounded by osteoblasts. In about 30% of cases, this bone tissue takes on a basophilic hue, referred to as “blue bone”. In cases of pathological fractures, tissue necrosis is more commonly seen.[6] [8] [13] In our reports, histopathological analysis was crucial for confirming the diagnosis, aligning with current literature findings.

The differential diagnosis includes other bone tumors, with hemorrhagic cystic alterations, such as osteosarcoma and chondroblastoma. However, the most important differential diagnosis is telangiectatic osteosarcoma, due to its image similarities and macroscopic appearance. Telangiectatic osteosarcoma can be distinguished from ABC through histological examination, which reveals the presence of malignant cells, absent in ABC.[13]

The choice of treatment for ABCs depends on the clinical manifestations and stage of the lesion.[6] Surgical intervention is often necessary due to the risk of significant bleeding, structural instability from fractures, and the potential for neurological compression.[7] The primary objective of surgical intervention is the complete resection of the cyst. This is because partial resections have been observed to have a recurrence probability of approximately 70%. In such cases, spinal reconstruction and stabilization may also be required.[4] [14]

In both cases we present, complete resection of the lesion was performed alongside spinal stabilization using pedicular screws and reconstruction of the anterior spine with a body cage. This allowed for adequate decompression of the neural structures, restoration of spinal stability, and prevention of further complications.

Selective arterial embolization (SAE) has emerged as a therapeutic option, either as a standalone treatment or as an adjunct to surgery. SAW involves the embolization of the ABCs blood supply, with a reported cure of approximately 80%. However, its use is limited in cases of myelopathy or spinal instability. In this procedure, the aneurysmal bone cyst is embolizing.[2] [13] In thoracolumbar lesions, embolization carries the risk of compromising the Adamkiewicz artery, while in cervical lesions, the vertebral arteries are a concern.[10] [13] In our first case, embolization was attempted but was unsuccessful.

Common postoperative complications include pulmonary infections, cerebrospinal fluid leaks, surgical wound infections, thromboembolic events, and release or failure of instrumentation.[15] In our first case, the patient developed deep vein thrombosis, which was treated with anticoagulation and a vena cava filter, as well as a surgical wound infection requiring surgical debridement and antibiotic therapy. The second one presented no postoperative complications.

The prognosis in ABC cases is influenced by factors such as the degree of resection, preoperative neurological impairment, and the location of the lesion. A complete resection generally improves outcomes, particularly in patients without severe preoperative neurological deficits.[9] [14] [16] [17]

 

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Conclusion

In cases of severe clinical manifestations, such as acute paraplegia, prompt and appropriate treatment, compromising tumor resection, spinal decompression, spinal reconstruction, and postoperative rehabilitation, can result in substantial neurological recovery. In cases where profound neurological impairments are present, appropriate surgical and rehabilitation can result in a complete resolution of deficits.

 

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Conflict of Interest

The Authors Report No Conflict Of Interest.

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Publication History

Received: 03 May 2023

Accepted: 20 March 2025

Article published online:
16 July 2025