Allergic contact dermatitis from ethyl chloride and sensitization to dichlorodifluoromethane (CFC 12).

Despite the widespread use of ethyl chloride as a local anesthetic and chlorofluorocarbons as propellants in medical and cosmetic aerosols, contact allergy to these 2 gases is rare. In a 30-year-old woman, an unusual itchy dermatitis appeared at all skin sites where a medical aerosol containing ethyl chloride had been briefly applied. Subsequent re-exposure to the spray and patch tests revealed contact sensitization to ethyl chloride and dichlorodifluoromethane (CFC 12). Histologic and immunohistochemical examinations of the test reaction were consistent with a T-cell-mediated allergic reaction. The low incidence of contact allergy to ethyl chloride and chlorofluorocarbons may be due to the rapid evaporation of these volatile gases, thus preventing intense and prolonged contact with the skin and consequently contact sensitization. A modified patch test procedure using perforated plastic chambers to allow gas evaporation is necessary to test volatile agents.