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AT-A-GLANCE

AT-A-GLANCE

  • Irritant dermatitis from wet-to-dry cycling is common in cold seasons.

  • Decreasing the duration and frequency of contact with irritants may improve symptoms of irritant contact dermatitis (as opposed to allergic contact dermatitis which requires complete avoidance to clear).

  • Innate immune signals from irritant dermatitis predispose to allergic dermatitis (allergic contact and atopic dermatitis).

  • Emollients accelerate recovery and may help prevent the complication of allergic dermatitis in infants.

  • Emollients used on normal skin over long intervals may predispose to irritant dermatitis.

  • Hardening, or disappearance of symptoms, often occurs with continued irritant exposure without any treatment.

  • Future understanding of ways to promote hardening could reduce the impact of allergic contact dermatitis and atopic disease which complicate irritant dermatitis.

INTRODUCTION

Irritant contact dermatitis is sometimes encountered as a primary diagnosis, but it is most important for its critical role in predisposing to atopic and allergic contact dermatitis.

When acute irritant dermatitis is the sole diagnosis, patients are often able to self-diagnose. There is obvious temporal relationship because irritant dermatitis manifests within hours of the causative exposure, and resolves within days of cessation of exposure. In contrast, allergic contact dermatitis may manifest days after exposure and persist for weeks. Consequently, accurate self-diagnosis of contact dermatitis is more common with irritant contact dermatitis than allergic contact dermatitis. The combination of straightforward self-diagnosis and shorter duration makes the presentation of irritant dermatitis for dermatologic consultation less common than that of allergic contact dermatitis.

T cells produce the inflammation of atopic and allergic contact dermatitis as part of the adaptive immune response. The adaptive response is influenced by upstream innate immune response. Irritant dermatitis provides the innate immune signals that predispose to allergic contact and atopic dermatitis. Therefore, the importance of irritant contact dermatitis is less recognition and treatment as a primary diagnosis, but its role in downstream dermatitis mediated by the adaptive immune response. Study of barrier disruption and the resulting innate immune signals should help us develop strategies to prevent irritant dermatitis so as to prevent more severe and disabling allergic and atopic dermatitis.

DEFINITIONS

Dermatitis is an inflammatory disruption of the epidermis related to physical or immunologic provocation. Dermatitis and eczema are often used interchangeably.1 Dermatitis appears as spongiosis histologically. There is impairment of the barrier functions of the skin, which results in increased transepidermal water loss.

As Fig. 25-1 illustrates, dermatitis is usually multifactorial. Irritant dermatitis results in barrier disruption which may predispose to higher concentrations of bacteria and yeast, and these microorganisms may stimulate immune response.2-4 Immune signals from barrier disruption also predispose to allergic contact dermatitis to chemical antigens,5 as discussed later in “Complications.”

Figure 25-1

Irritant dermatitis leads to barrier disruption that promotes immune response to bacteria and yeast, as well as to chemicals in contact with the skin. Dermatitis often results from ...

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