Abstract

Background: Spine aneurysmal bone cysts (SABC) are osteolytic tumor-like lesions with cystic, blood-filled cavities that represent 15% of all primary spinal bone tumors. The sacrum is a rare site for SABC, and sacral lesions typically carry higher morbidity rates. Here, a 19-year-old female with a large primary multisegmental sacral SABC was successfully managed with 2-staged endovascular embolization.

Case Description: A 19-year-old female presented with progressive worsening of axial lumbosacral pain, and a left L5/S1 radiculopathy. The lumbosacral computed tomography and magnetic resonance studies showed a large (10 cm [AP] × 11 cm [Tr] × 12 cm [CC]) heterogeneous, osteolytic lesion containing multiple fluid-fluid levels. The biopsy confirmed the diagnosis of a primary SABC. She was treated with a 2-staged endovascular embolization that resolved her pain. This was followed by radiographic confirmation of occlusion of the SABC.

Conclusion: A 19-year-old female presented with an atypical SABC that was successfully managed with 2-staged endovascular embolization.

Keywords: Embolization, Endovascular treatment, Sacral aneurysmal bone cyst, Spine

INTRODUCTION

Most spine aneurysmal bone cysts (SABC) occur in patients under 20 years of age. They typically present with focal pain and neurological deficits reflecting their locations. SABC represent 15% of all primary bone spine tumors, and only rarely involve the sacrum (i.e., 3%).[ 8 ] Computed tomography (CT)/magnetic resonance (MR) studies typically document multiple cyst-fluid levels within the posterior elements or vertebral body at a single spinal level. However, sacral lesions are often multisegmental and extend into the sacral canal. Their treatment, consisting variably of biopsy, curettage, excision, embolization, and/or denosumab, is more problematic.[ 1 , 5 , 7 - 11 , 13 ] Here, a 19-year-old female following MR/CT studies and a biopsy-proven sacral SABC was successfully treated with 2-staged endovascular embolization.

CASE DESCRIPTION

A 19-year-old female presented 6 months of worsening, nocturnal, lumbosacral and left-sided L5/S1 pain, and weakness. The CT scan showed an extensive (i.e., 10 cm [AP] × 11 cm [Tr] × 12 cm [CC]) heterogeneous lytic lesion containing multiple cysts with fluid levels in the sacrum with attendant cortical destruction and invasion of the sacral canal. The lesion extended anteriorly to the sacrum into the pelvic cavity (i.e., with ill-defined borders), laterally into the iliac bones, superiorly into the L5 vertebral body, and inferiorly into S4 [ Figures 1a - c ]. On MR imaging (MRI), the inhomogeneous cysts were filled with moderate/high signal intensities (i.e., fluid levels on T1/T2 images), separated by multiple septae [ Figure 1d ].

Figure 1:

(a) Computed tomography (CT) axial view, (b) sagittal view, and (c) 3D reconstruction showing an extensive sacral lytic lesion extending to the iliac bones. (d) T2 magnetic resonance imaging(MRI) sagittal view showing multiple cystic cavities with fluid levels extending into the sacral canal and peritoneal cavity.

Biopsy and pathology

Percutaneous biopsies performed at multiple lesion locations yielded the diagnosis of a primary SABC (i.e., typical histological pattern for ABC and with no precursor lesion identified).

Two-Stage endovascular embolization

Digital subtraction angiography of the infrarenal aorta identified feeders from the posterior rami of both internal iliac arteries, (i.e., mainly from the left) [ Figure 2 ]. The first endovascular embolization included; (1) arteriography of the left internal iliac artery with super-selective catheterization of 2 rami, (2) followed by infusion of 500 µm polyvinyl alcohol (PVA) particles. The patient’s axial/radicular pain dramatically improved enabling her to ambulate and undergo physiotherapy. Although the 6-week post-embolization contrast CT showed signs of healing (i.e., partial peripheral ossification without lesion growth), we elected to perform a 2^nd endovascular embolization that included; (1) microcatheterization of feeders from the posterior rami of both internal iliac arteries and (2) followed by embolization with 355–500 µm PVA particles. Each treatment required 2 days of hospitalization. She sustained no complications from either procedure.

Figure 2:

(a) Intra-Arterial computerized tomography (CT) with 3D reconstruction identifying culprit arterial branches. (b) Digital subtraction angiography (DSA) showing catheter and microcatheter tip with stasis in one of the arterial branches. Gross calcification of the aneurysmal bone cysts (ABC) is seen on the left. (c) DSA showing a branch from the right internal iliac artery which was super selectively catheterized and embolized with polyvinyl alcohol particles ( PVA) particles.

Postoperative course

Postoperatively, although the left-sided L5/S1 motor deficit remained, the patient’s pain significantly improved. Multiple follow-up CT exams obtained up to 2 years later showed progressive healing, (i.e., bone formation within the ABC and peripheral sclerotic bony changes) [ Figure 3 ].

Figure 3:

(a) Non-contrast computerized tomography (CT) axial view, (b) sagittal view and, (c) 3D reconstruction at 24 months post treatment showing signs of healing (ie bone formation within the aneurysmal bone cysts (ABC) and peripheral sclerotic bony changes).

DISCUSSION

Here, a 19-year-old female demonstrated L5/S1 pain, and motor deficits attributed to a sacral SABC (i.e., L5–S4 with a total volume of 680 cm³). This SABC extended into the iliac bones, sacral canal, and peritoneal cavity (i.e., Enneking type 3 lesion with an aggressive invasion of adjacent tissues).[ 4 ] Our literature review yielded 7 retrospective series and 5 case reports of sacral SABC; these lesions are often multisegmental and can grow to impressive dimensions thus resulting in significant neurological deficits (i.e., myeloradiculopathy/paraparesis with sphincter dysfunction) [ Tables 1 and 2 ].

Table 1:

Case reports on sacral ABCs.

Table 2:

Cases on sacral ABCs reported on retrospective series.

Increase in endovascular arterial embolization of sacral ABC to limit morbidity of surgery

The large extent of SABC, associated with increased perioperative morbidity (i.e., risks of gross total en bloc excision or curettage resulting in life-threatening intraoperative bleeding, and/or significant neurologic deficits) has prompted greater interest in alternative treatment with endovascular arterial embolization. We identified 14 sacral ABC cases from the literature that were successfully treated with SAE (i.e., spinal arterial embolization) performed in 1–3 stages; the most significant improvement usually occurred within the first few days following the first embolization stage.[ 2 , 3 , 6 , 12 ] In our SABC case, to minimize the risk associated with surgery, we performed a 2-staged endovascular embolization procedure. Although a significant positive clinical response was obtained after the first procedure, we chose to perform second SAE 6 weeks later. Notably, the patient continued to neurologically improve over the next 2 years, whereas the postoperative contrast CT studies confirmed progressive healing of the SABC lesion.

CONCLUSION

We successfully treated a 19-year-old female’s large multisegmental sacral ABC with 2-staged endovascular embolization.

Declaration of patient consent

Patient’s consent not required as patient’s identity is not disclosed or compromised.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation

The author(s) confirms that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

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