Dural-Invasive spinal metalloma following titanium internal fixation: a rare case report and systematic literature review.

Abstract

BACKGROUND: Spinal metalloma is a rare, space-occupying inflammatory pseudotumor caused by wear or corrosion of metallic spinal implants, which can lead to severe neurological compression. Although previously reported, cases arising from a biocompatible titanium alloy construct without evidence of implant failure or instability, and exhibiting direct dural invasion, are exceptionally rare, and their pathophysiology remains to be elucidated. CASE PRESENTATION: We report a 75-year-old male who presented with progressive low back pain, left lower limb radiculopathy, and cauda equina syndrome four years after undergoing an L3-5 posterior decompression, fusion, and titanium alloy instrumentation for lumbar spinal stenosis. Imaging studies ruled out infection, neoplasm, and implant loosening or breakage, but revealed a new, compressive intraspinal mass at the L2-3 level. Revision surgery revealed a grayish-black, sand-like necrotic mass severely compressing and invading an attenuated dura mater. Pathological examination confirmed tissue changes consistent with spinal metallosis. The patient’s neurological symptoms improved significantly postoperatively. RESULTS: A systematic literature review identified 8 similar cases. However, the present case is the first to be reported arising from a stable, all-titanium construct and featuring dural invasion. CONCLUSIONS: A high index of suspicion for spinal metalloma should be maintained for patients presenting with new or progressive neurological symptoms after spinal surgery, even with a stable titanium alloy construct. Definitive diagnosis relies on histopathology, and adequate neurological decompression is the key to effective treatment.