Frostbite occurs on the ends of the limbs, especially on exposed areas, which are particularly susceptible to frostbite. In these areas, the patient develops localized, obvious hard lumps that are relatively small in extent, but there is no obvious discoloration of the skin that occurs, and by this time it will already be present, and when it encounters warmth and heat, an itching sensation will occur. With further aggravation of the disease, skin discoloration will occur in these areas, and the hard nodules will slowly become larger. Patients may also notice a gradual increase in itching, especially when soaking their feet, going under the covers, or in a warm room. As the disease continues to progress, there may be visible nodules, or even blisters and skin breakdown.