A rare case of delayed hypersensitivity reaction to metal ions secondary to a remnant pedicle screw fragment after spinal arthrodesis.

Delayed hypersensitivity reaction to metal ions is rare and has been mostly documented among patients undergoing total joint arthroplasty with metal-on-metal bearing surfaces. Nonetheless, to our knowledge, only a few cases associated with spinal arthrodesis have been reported in the literature. The aim of this case report was to describe the clinical features of a rare case of delayed-type hypersensitivity reaction to nickel that occurred after an extraordinarily long period of time (approximately 15 years) after spinal arthrodesis. Here, we present a 38-year-old patient who was referred to us with a diagnosis of delayed-type hypersensitivity reaction to nickel that was established by a skin patch test. The chief sign and symptoms of the patient were allergic contact dermatitis along with intractable, generalized itching that started several months ago. The medical history revealed that the patient had undergone spinal arthrodesis using rods and pedicle screws approximately 15 years ago, followed by revision surgery to remove the implants. Radiological examination showed a remnant pedicle screw fragment at the third lumbar vertebra that had broken off during the removal of implants nine years ago. However, the signs and symptoms of metal hypersensitivity started shortly before the patient was referred to our hospital. We decided to remove the screw fragment as allergic contact dermatitis was refractory to medical treatment. On postoperative day one, the itching was completely resolved, although the skin patch test remained positive.