Mechanical and Thermal Injury

Abstract

The skin is constantly subjected to both internal and external mechanical forces, so that for experimental purposes it may be impossible to determine what constitutes the normal resting state. These forces are likely to be as important in the maintenance of the structural integrity of the connective tissues of the skin [1,2] as they are with bone, which becomes demineralized during the protracted absence of normal gravitational force during space travel [3]. In contrast to events in the whole organism, isolated human dermal fibroblasts in culture make more collagen when subjected to reduced gravity [4]. Many normal biochemical functions of the skin are dependent on appropri-ate mechanical forces, and when these become excessive, as in lymphoedema, protease inhibitors are released with many deleterious consequences [5].Healthy skin is well adapted to resist the adverse effects of a wide range of mechanical injuries [6]. These include friction, pressure, contusion, laceration, suction and vibration. The clinical consequence of injury will depend on characteristics of the noxious stimulus, such as its intensity and duration. Factors related to the skin also influence the response; thus, the same degree of friction may produce a blister in one person but no visible change in another. Time is required for adaptive responses, such as callus formation and lichenification, to occur.

Child abuse and trichotillomania

“…The most common dermatological signs of child abuse are bruises and abrasions then lacerations, scratches, soft tissue swellings, strap marks, haematomas, burns, and bites 2. Hair loss as a manifestation of child abuse is usually described in association with underlying scalp bruising or tenderness 3. In this boy, however, the force applied by the perpetrator was insufficient to cause any damage to the underlying soft tissue: localised hair loss was the sole manifestation of abuse.…”

Erythema ab igne in a rural Indian woman

“…[7] Squamous cell carcinoma and other malignancies have been reported in longstanding cases. [2,5] EAI in patients of internal malignancy has been reported. [8] However, EAI is not a marker of internal malignancy and does not meet Curth's criteria.…”

“…[1,2] It clinically presents as reticular, pigmented dermatoses, rarely may present as bullous lesions. [3] It should be differentiated from vasculitis, livedo reticularis, [1] port wine stain, cutis marmorata and poikiloderma.…”

“…EAI poses an occupational hazard for silversmiths, jewelers, bakers and kitchen workers. [2] Several cases of heat radiation from laptops [9] and footbaths with Chinese herbal remedies [10] causing EAI have been documented.…”

Radiotherapy induced keobernisation of vitiligo

“…The response should be reproducible and not limited to one type of trauma. [2] It is seen in psoriasis, vitiligo, lichen planus etc. Many forms of mechanical/physical/chemical/allergic trauma, incision and laceration, skin tests, burns, freezing, UV light and ionizing radiation have been implicated.…”