Chronic Irritant Contact Dermatitis Research Articles

CLINICAL IRRITANT CONTACT DERMATITIS SYNDROMES

Irritant contact dermatitis (ICD) is a frequent and important condition in general and occupational dermatology. 18,33 It is probably more frequent than allergic contact dermatitis, although reliable data are still very limited. Despite their different pathogenesis, allergic and irritant contact dermatitis, especially of the chronic type, show a remarkable similarity with respect to clinical appearance, histology, 7,8 and immunohistology. 9,44 Frequently, even therapy is similar. 6,36 In contrast to allergic contact dermatitis, ICD is defined as being the result of a primarily unspecific damage to the skin (Table 1). It is not a clinical entity, but rather a spectrum of diseases. The clinical aspect of ICD is determined by the dose-effect relationship. 47 The morphology of acute ICD shows erythema, edema, vesicles that may coalesce, bullae, and oozing. Necrosis and ulceration is only seen with primary irritants. The clinical features of chronic ICD include redness, lichenification, excoriations, scaling, and hyperkeratosis. Most frequently affected by ICD are the hands, as they are the human tools that interact with the environment most and have intensive contact to irritants; however, spilling of fluids may irritate the forearms or other body sites, especially when fluids soak through work clothes. The incidence of irritant dermatitis correlates with irritant exposure of the workers in a given profession. 28 Some high-risk occupations are caterers, 11 furniture industry workers, 23 hospital workers 24 (nurses, 31 cleaners, 49 kitchen workers), hairdressers, 51 chemical industry workers, 10 dry cleaners, 2 metal workers, 13,14,21,27 florists, 4 and warehouse workers. 3 Airborne irritant dermatitis develops in irritant-exposed sensitive skin, mostly the face and especially the periorbital region. 15,34 Irritant dermatitis caused by dust may mimic textile dermatitis, with lesions most prominent in sites with close skin-garment contact, such as the axilla, the gluteal region, or the thighs.

The modulation of skin irritation

Irritant contact dermatitis (ICD) is a multifactorial disease, the onset and modulation of which depend on both endogenous and exogenous factors. Among the former, age, race, site, sex and history of dermatitis may all be important. Such variables can now readily be quantified by objective noninvasive techniques, such as measurement of transepidermal water loss (TEWL). Moreover, effects of irritants on the epidermis are related to the particular chemical properties of each molecule, contributing further to clinical heterogeneity. Release of cytokines and mediators may be initiated by a number of cells, including living keratinocytes and those of the stratum corneum, thus modulating inflammation and repair. Furthermore, differences in mechanisms of inflammation between acute and chronic ICD may exist, the former being characterized predominantly by inflammation, the latter by hyperproliferation and transient hyperkeratosis. These findings may explain the complexity and difficulty of investigating ICD. Better understanding and quantification of these mechanisms may lead to identification of high-risk individuals and more effective prevention and treatment.

Post-application occlusion substantially increases the irritant response of the skin to repeated short-term sodium lauryl sulfate (SLS) exposure.

Occlusion often, but not always, enhances percutaneous absorption and thus may facilitate skin irritation. Quantitative data about the impact occlusivity may have on minimal irritant stimuli to which the skin is exposed in daily life, and which may lead to chronic irritant contact dermatitis, are however lacking. Irritant stimuli were administered by repeated application of sodium lauryl sulfate (SLS) in an open application procedure. After the open exposure, the skin was either left open or occluded with plastic. Skin irritancy was assessed by means of visual grading and by transepidermal water loss (TEWL) measurements. Post-exposure occlusive treatment markedly enhanced the irritant response. 5 consecutive daily applications produced more irritation, with or without occlusion, than alternate day application. Occlusion may be a relevant factor in the development of irritant contact dermatitis from certain chemicals.

Do topical corticosteroids modulate skin irritation in human beings? Assessment by transepidermal water loss and visual scoring

The efficacy of topically applied corticosteroid formulations of different potencies on irritant skin reactions was assessed in human beings. Chronic irritant contact dermatitis was produced by repeated application of a low-molarity sodium lauryl sulfate solution. Neither corticoid nor vehicle inhibited visible response to the irritant. Barrier function, as measured by transepidermal water loss, was impaired. The corticoid formulations and the vehicles did not significantly influence barrier function. These data raise the question of the value of certain topical corticoids and vehicles in chronic irritant contact dermatitis when the irritant is not removed.