IRRITANT CONTACT DERMATITIS
Irritant contact dermatitis is one of the most commonly encountered dermatoses in the dermatology clinic. Its true incidence is unknown. Irritant contact dermatitis can be caused by a multitude of factors, and the morphology of its appearance can be varied. One of the most common forms of irritant contact dermatitis is seen on the hands and is caused by occupational exposures to irritant chemicals or excessive hand washing.
Clinical Findings: Irritant contact dermatitis can occur at any age. Some studies show that women are more commonly affected. There is no racial predilection. There are many exposures that can eventually lead to the development of irritant contact dermatitis. The final clinical manifestations are similar despite the different instigating chemicals. Variations exist in the location of the dermatitis. The hallmark of irritant contact dermatitis is xerosis. Once the skin dries out to a certain point, it becomes inflamed. This leads to the clinical picture of dry pink or red patches. On the hands, painful fissures or splits may occur within the skin lines. Diaper dermatitis in infants is one specific form of irritant contact dermatitis. The wet diaper rubbing against the child’s buttocks and legs can cause skin irritation, red patches, and occasionally erosions. The child can become irritable with pruritus and is at higher risk for secondary bacterial infections.
Many chemicals are direct irritants to the skin, and injuries from these agents are occasionally seen in a dermatologist’s office. Exposure of the skin to hydro- chloric acid results in skin cell death, necrosis, and inflammation. This, in turn, leads to the development of red patches or plaques with varying amounts of erosion and ulceration. These patients often receive care in an occupational work setting or in the emergency room. The same can be said for exposure of the skin to strong basic chemicals such as sodium hydroxide. Basic chemicals can cause an irritant contact dermatitis that is directly related to the necrotic effect of the chemical on the skin surface.
One of the most common causes of irritant contact dermatitis is frequent hand washing. The use of soaps removes the natural oils and waxes that the skin pro- duces as a way of physiologically keeping the skin from drying out. Once the removal of these oils outweighs their production, dryness begins to set in. If the skin is not given enough time to repair itself, the epidermis continues to dry out and becomes inflamed. Pink to red patches are evident, and, as the irritation continues, the dryness worsens until fissuring and cracking occur.
Ring dermatitis is another common form of irritant contact dermatitis. It is believed that soap residue builds up between the surface of the ring and the skin. This prolonged contact causes an irritant contact dermatitis underlying the ring. It can be misdiagnosed as an allergic contact dermatitis, and on initial presentation, these two forms of dermatitis cannot be differentiated. The main differential diagnosis is between an irritant and an allergic contact dermatitis. The two have similar clinical appearances and can be almost impossible to differentiate. Irritant contact dermatitis typically has an acute onset and a decrescendo resolution, unless there is repeated exposure to the irritant. Allergic contact dermatitis usually has a crescendo-decrescendo clinical course. These patterns can be helpful in differentiating the two conditions.
Pathogenesis: Exposure to an irritant chemical, whether an acid or a base, or repeated exposure to soap and water leads to a similar inflammatory cascade. The damaged keratinocytes release myriad inflammatory cytokines. The intensity of the reaction is based on the concentration of the irritant and the exposure time. The recruitment of T cells occurs later in the time course of irritant contact dermatitis, when compared with allergic contact dermatitus.
Treatment: The goal of treatment is to remove the skin from exposure to the irritant. Barrier creams and frequent diaper changes may be all that is needed to resolve irritant contact diaper dermatitis. Hand dermatitis can be treated with a combination of moisturizers, topical corticosteroids, and avoidance of frequent hand washing. If these changes can be accomplished, the prognosis is excellent. Workers with potential occupational exposures to irritant chemicals must be properly trained in handling them and given the correct protective gear to prevent exposure.