Review Question - QID 104248

The patient presents with a localized rash consistent with contact dermatitis. The most common metal to cause this type IV hypersensitivity reaction is nickel, which is the base metal of most costume jewelry.

Contact dermatitis results from contact with an allergen. Triggers include poison ivy, poison oak, nickel, detergents, cosmetics, rubber, and latex. It often presents days to weeks after the initial exposure since it is a type IV hypersensitivity reaction. On physical examination it appears as a pruritic, erythematous rash with vesicles at the site of exposure. These rashes may become superinfected with skin flora when scratched resulting in pus-filled vesicles, thus scratching should be avoided. Lesions always occur at the site of contact with the antigen, and this is often a clue to etiology.

Figure A depicts the classic appearance of a contact dermatitis from nickel earrings. Note the erythematous appearance of this rash and the localization to the exact site of the exposure. Illustration A depicts common characteristics of type I-IV hypersensitivity reactions.

Incorrect Answers:
Answer 1: Platinum is not known to cause contact dermatitis as often as nickel.
Answer 2: Gold is not known to cause a contact dermatitis as often as nickel, but would still be a type IV hypersensitivity reaction.
Answer 3: Latex may cause a contact dermatitis but given the location, metal earrings are more likely to be the culprit.
Answer 4: Cosmetics can cause a contact dermatitis, but the reaction would still be a type IV hypersensitivity reaction.