A handheld appliance suitable for skin treatment and/or personal care operations comprises an applicator structure having a thermally conductive element supported so as to be exposable to controlled release of pressurized fluid within a gas-expansion chamber. The just-expanded gas causes an endothermic reaction in which heat is removed from the applicator. The applicator is usable to then draw heat energy from skin, etc. When applied to skin, a numbing effect is experienced which can ease pain associated with depilation, discomfort associated with exfoliation, be useful in treating wounds, etc.