Three days after a dental appointment in which a latex rubber dam was used, a child presents with new burning lesions around the mouth. What type of hypersensitivity reaction is this?

Correct answer: A. Type IV hypersensitivity reaction

• A. CORRECT. TYPE IV (delayed/cell-mediated) hypersensitivity occurs 48-72 hours after exposure. It is mediated by sensitized T lymphocytes (not antibodies) releasing cytokines. The burning skin lesions 3 days after latex contact = classic Type IV contact hypersensitivity (contact dermatitis).
• B. INCORRECT. Type III (immune complex) involves antigen-antibody complexes depositing in tissues — examples: lupus, serum sickness. Delayed contact reactions are Type IV.
• C. INCORRECT. Type I (IgE-mediated) is IMMEDIATE (within minutes) — urticaria, rhinitis, anaphylaxis. The initial acute reaction was Type I.
• D. INCORRECT. Type II (cytotoxic) involves antibodies targeting cell surfaces — examples: hemolytic anemia, Goodpasture syndrome. Not relevant here.