Pressure/Friction : Pressure or friction on a localized area of skin can producea blister if the pressure/friction is acute as on wearing tightnew shoes or undertaking hard manual labour. If thepressure/friction is chronic and recurrent it can lead to acorn or a callosity.
Burns : These are produced if an individual gets exposed to heatabove 60°C. A brief contact may result only in pain anderythema, while a higher temperature or a prolongedcontact leads to blistering or deep ulceration. The intensity and the extent of damage will be proportional to thetime and the area of exposure. The blisters are subepi-dermal.
Erythema ab Igne : It occurs when the exposure to heat occurs repeatedly andover a prolonged period and the heat stimulus is mild. Thearea exposed to the heat develops a reticulate pattern ofcrythema and hyperpigmentation. It is more common in thecold climates.
Frost Bite : It results when a normal individual gets exposed to afreezing cold temperature for a long period. The peripheralparts of the body become numb and white during theexposure and develop erythema, oedema, blisters andgangrene on rewarming.
Chilblains : These appear on exposure to cold if the person has anincreased sensitivity to cold. The lesions consist of painfulerythematous and oedematous areas on the dorsal aspectsof the toes and fingers, which turn brown-black within afew days. Healing occursspontancously without scarring