A rare case of type IV hypersensitivity: Prilocaine allergy

Allergic reactions caused by local anesthetics are quite rare and these reactions often manifest as Type I (immediate-type) hypersensitivity; however, Type IV (delayed-type) hypersensitivity reactions also hold clinical significance. Type IV reactions are generally T-lymphocyte mediated and symptoms appear hours or days after antigen exposure. In this case report, a rare Type IV hypersensitivity reaction to prilocaine, an amide-type local anesthetic, is described. The patient presented to our center due to the delayed-onset skin lesions that developed after previous surgical procedures and was evaluated through comprehensive allergy testing. A positive delayed-type reaction to prilocaine was observed in the intradermal and patch tests; however, no reaction was detected in the provocation test performed with mepivacaine. This highlights the importance of careful selection of local anesthetics and consideration of Type IV hypersensitivity. Sharing such cases contributes to increased clinical awareness.