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Preoperative X-ray and CT.. (a) X-ray AP view showing a lytic lesion involving the left L5 vertebral body illustrating a winking owl sign (arrow) (b) The reconstructed lumbar CT scan reveals a lytic expansive lesion involving the L5 vertebral body and left pedicle. Left: sagittal view, and right: axial view.
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Plain radiographs showed an osteolytic lesion involving the left L5 vertebra with a winking owl sign observed on anteroposterior(AP) views (Fig. 1a). Computed tomography (CT) revealed pathological fractures of the L5 vertebral body and left pedicle along with osteolytic changes (Fig. 1b).
MRI of the lumbar spine showing characteristic findings of aneurysmal bone cysts.. T2-weighted sagittal images and T2-weighted axial image centered on the L5 pedicle revealing a cystic lesion involving the left L5 vertebral arch, pedicle, and vertebral body with fluid-fluid levels (arrow).
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Magnetic resonance imaging (MRI) revealed a lobulated lesion with fluid-fluid levels in the left vertebral arch, pedicle, and vertebral body of the L5 vertebra with high and low signal intensities on T2- and T1-weighted images, respectively. (Fig. 2a, b).
Preoperative embolization and Pathology photograph.. (a) Embolization of the bilateral L4 lumbar arteries and left iliolumbar artery was performed. (b) Intraoperative photograph after resection of the tumor. The left L5 nerve root was preserved, and the cage was inserted cephalad to the L5 root and then expanded. (c) In a low-power view, fibrous connective tissue associated with capillary proliferation (white arrow) and fibrin deposition (black arrow) are observed. These findings are consistent with the diagnosis of an aneurysmal bone cyst. (d) In a high-power view, there is fibrous connective tissue associated with capillary proliferation. No malignancy is observed.
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We performed preoperative arterial embolization of the bilateral L4 lumbar arteries and the left iliolumbar artery to prevent intraoperative hemorrhage (Fig. 3a). Using intraoperative navigation to identify tumor margins, a thorough curettage was performed to remove the tumor (Fig. 3b). The final pathological diagnosis of ABC was made by confirming the fibrous connective tissue accompanied by capillary proliferation and partial fibrin deposition, with no signs of malignancy (Fig. 3c, d).
Postoperative X-ray and MRI.. (a) Postoperative X-ray of the lumbar spine (b) Postoperative MRI two years after surgery with no signs of recurrence. (c) Postoperative CT two years after surgery showing interbody fusion between L4 and S1 within the expandable cage and by the right posterolateral fusion mass.
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Pedicle screws were inserted into L4 and S1, and an expandable cage packed with autologous bone chips was placed between the vertebral bodies to reconstruct the lumbar spine's anterior strut (Fig. 4a). At two years follow up, CT and MRI showed no apparent signs of recurrence (Fig. 4b, c).
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