Titanium Alloy, Dermatitis, Allergic Contact, Granulomatous
Contact dermatitis; Titanium
Delayed-type hypersensitivity reactions (type IV by Coombs and Gell) to metals like nickel or cobalt are quite common. In contrast, titanium is regarded as very stable material with almost no potency to elicit allergic contact dermatitis, thus often recommended as a substitute for patients suffering from nickel contact allergy and in need of a metal implant. However, it is discussed if titanium can elicit granulomatous reactions, which have been proposed as type V allergic reactions according to the classification of types I–IV hypersensitivity reactions by Coombs and Gell. These immune reactions are elicited by macrophages reacting to foreign body particles and usually appear several weeks after the uptake of the allergen, for example, as nodules mimicking hypertrophic scars or keloids after skin piercing.