Type IV Titanium Hypersensitivity: Rare, or Rarely Detected?

The presented review aims to summarize the current knowledge of hypersensitivity to titanium - a material widely used in medical applications thanks to its exceptional chemical stability, resistance to corrosion, low specific weight and high strength. The hypersensitivity to metals is usually caused by the Type IV immunopathological reaction. Case reports on allergic reactions to titanium are rare but the actual occurrence can be expected to be much higher, especially due to its problematic detection. Although cutaneous patch tests are widely accepted and used for the diagnosis of hypersensitivity of numerous metals (e.g. Ni), it is notoriously unreliable in case of allergies to titanium, which may be associated with the low percutaneous transport of titanium and its salts. The Lymphocyte Transformation Test has superior sensitivity but it remains mostly unknown among clinicians and there are not many laboratories capable of performing it. This review presents numerous case reports indicating, in combination with the above-mentioned facts, that hypersensitivity to titanium should be considered as a possible cause also in non-specific problems associated with titanium implant failure. Key words: titanium, allergy, patch test, lymphocyte transformation test.