4. 19-year-old J.G. has been treating plantar warts at his heels with salicylic acid 40% liquid at bedtime for 2 months with minimal improvement. You propose complementary treatment with liquid nitrogen. You instruct J.G. that he may experience redness, tenderness, blistering, crusting and/or hypo- or hyperpigmentation. What other adverse effects may result from cryotherapy of plantar warts?