In regions of the body where the stratum corneum is thinner, a repeated friction force will cause the stratum corneum to erode and, instead of a blister, an erosion or abrasion will occur. Moisture and lubricating substances present on the skin surface are additional factors. With a greater frictional force, fewer cycles of rubbing against the skin are needed to produce a blister. Moisture on the skin surface may either increase the friction force or, in the case of very moist skin, decrease it temporarily by providing lubrication. Heat, sweating, and maceration of the skin may predispose to friction blister formation.
Midepidermal necrosis is evident.
The blister cavity is filled with a clear transudate. High mitotic activity is present in the base of the blister about 30 hours after formation of the friction blister. By 48 hours, a new granular layer has developed. By 120 hours, a new stratum corneum is seen. A significant inflammatory infiltrate is not seen as long as the blister site is not secondarily infected.