Cryosurgery (or cryotherapy) is a medical procedure that uses extremely cold temperatures—most often via liquid nitrogen—to freeze and destroy abnormal or diseased tissue. Main applications • Benign and precancerous skin lesions: Warts, skin tags, molluscum contagiosum, seborrheic keratoses, and actinic keratoses. • Skin cancers: Certain superficial basal cell or squamous cell carcinomas. • Internal tumors: Treatment of certain cancers (such as prostate, liver, or kidney cancer) using thin instruments called cryoprobes, often guided by imaging (ultrasound or MRI). How it works • On the skin: The doctor applies the cooling agent (approximately -196°C for liquid nitrogen) using a cotton swab or a spray device. The cold causes ice crystals to form inside the cells, leading to their rupture and destruction, followed by gradual elimination through the skin.