Healthy skin is able to withstand the effects of a variety of mechanical forces, such as friction, pressure, contusion and vibration. However, when the force is of sufficient intensity or duration, mechanical injury may occur. Phenomena such as the isomorphic (Koebner) response and Nikolsky sign are of interest to dermatologists when considering the underlying pathology. Other conditions are important to recognize, as they may potentially be confused with skin cancers (black heel, spectacle frame acanthoma) or important dermatological diseases (foreign body reaction, friction blisters, sclerodermiform reaction, semicircular lipoatrophy). Mechanical insult to the skin may reflect an occupational hazard, such as the diverse skin reactions to musical instruments, traumatic effects of sports, hypothenar hammer syndrome and hand–arm vibration syndrome. The diverse presentations of cutaneous mechanical injury are discussed in this chapter.

Keywords mechanical skin injury, isomorphic (Koebner) response, Nikolsky sign, mechanical properties of skin, callosities, corns, calluses, friction blisters, black heel, black palm, skin reactions to musical instruments, hypothenar hammer syndrome, Achenbach syndrome, spectacle frame acanthoma, semicircular lipoatrophy, acne mechanica, traumatic effects of sports, foreign body reaction, paraffinoma, sclerodermiform reaction, fibreglass dermatitis, complications of tattoos, hair as a foreign body, hand–arm vibration syndrome, piezogenic pedal papules