Various agents may cause a delayed allergic reaction of the skin. This is an example of one of the rarer ones: the eczematous, itchy patch developed after infiltration analgesia with prilocaine for minor operation. The aetiology was confirmed by patch testing. The patient had become sensitized to prilocaine during multiple dental operations at the dentist. For reference: http://www.iki.fi/raimos, see publications/allergy.