Metastatic Melanoma Epidural Tumour Regression Following Percutaneous Radiofrequency Ablation

Abstract

Percutaneous radiofrequency ablation of spinal metastases is an emerging treatment for patients with painful metastatic spine disease. It is typically performed for patients who have not responded to conventional treatments or who have contraindications to radiotherapy. Destruction of the posterior wall of the vertebral body and epidural disease may be considered relative contraindications for radiofrequency ablation. This is due to the difficulty in achieving satisfactory ablation balanced against the risk of neural injury. We describe a case of metastatic melanoma with an expansile lytic metastasis and epidural tumour extension at the L4 vertebral body level resulting in severe central canal stenosis. This was successfully treated with percutaneous radiofrequency ablation and vertebral augmentation. The patient reported significant pain relief post-procedure and follow-up MRI at two months demonstrated local tumour regression, epidural disease resolution and improved spinal canal dimensions. To the best of our knowledge, this is the first report of epidural disease resolution from metastatic melanoma following radiofrequency ablation and emphasises the potential benefits of ablation therapy even in the presence of canal stenosis and epidural metastatic disease.

Keywords: back pain; bone metastases; interventional radiology; malignant melanoma metastasis; musculoskeletal radiology; radiofrequency ablation; spinal metastases.

Figure 1. Pre-treatment portal venous phase CT demonstrating a destructive lesion within the L4 vertebral body with enhancing epidural soft tissue tumour extension (black arrow) resulting in moderate central canal stenosis.

Figure 2. Pre-treatment parasagittal contrast-enhanced T1-weighted image (A), T1-weighted (B) and STIR-weighted (C) acquisitions demonstrating an expansile metastasis within the diffusely infiltrated L4 vertebral body and epidural metastatic disease (arrow heads) which result in moderately severe central canal stenosis (white arrow).

STIR, short TI inversion recovery

Figure 3. Axial T2-weighted image demonstrating a soft tissue mass extending into the epidural space (white arrow) that results in moderate central canal stenosis.

Figure 4. Lateral fluoroscopic images demonstrating bipedicular ablation needles and thermocouple position (A) and vertebral augmentation with methyl methacrylate (B).

Figure 5. Post-treatment sagittal STIR-weighted (A) and axial T2-weighted (B) images demonstrating reduced tumour volume, resolution of epidural disease and improved canal dimensions (white arrow).

STIR, short TI inversion recovery