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

backgroundSpinal 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.

resultsA 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.

conclusionsA 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.