Answer: B
Irritant contact dermatitis (ICD) is a localized inflammatory skin reaction to physical or chemical agents. It is the most common form of contact dermatitis and is distributed on the hands more frequently than allergic contact dermatitis.10,11 Infants are the most sensitive to skin irritants and therefore prone to developing ICD.12 In the adult population, individuals involved in “wet work” are at high risk for occupational ICD.13 “Wet work” is defined as washing hands, wearing gloves, or touching water for more than 2 hours per day. 10 This commonly includes workers in health care, mechanics, cleaning, or food industries. 13 ICD commonly affects women more than men, likely due to increased domestic and occupational exposures.11
The pathophysiologic mechanism of ICD is dependent upon innate immune system activation. As such, ICD can develop with the first exposure to a skin irritant, unlike ACD, which requires initial sensitization.3 The first step in acute ICD development is damage to the epidermal skin barrier, resulting in cytokine release and leukocyte recruitment.14 Exposure to water causes the stratum corneum to swell and the skin lipids to separate.15 Detergents and alkaline substances also damage hydrophobic lipids in the skin via saponification, and acids act by denaturing proteins. Physical irritants such as fiberglass and wood break the skin through repetitive trauma. Environmental factors also play a role in ICD pathogenesis. In high heat and humidity, the skin barrier is more susceptible to irritant entry. However, cold temperatures also contribute to ICD because increased water loss compromises the skin barrier.16 The pathogenesis of chronic ICD is more poorly understood, but the long-term exposure to an irritant is believed to down-regulate immune responses and induce skin proliferation.17 The acanthosis and hyperkeratosis that result are known as a “hardening phenomenon.”18
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The clinical presentation of ICD is highly variable depending on irritant strength and skin sensitivity. The mildest form involves skin dryness and erythema, and the most severe presentation includes skin necrosis. In acute ICD, patients often complain of a stinging or burning pain. It is characterized by vesicles, edema, erythema, and scaling. Corrosive chemicals can elicit ulcers and necrosis. Chronic ICD presents with dry, fissured skin, hyperkeratosis, and a glazed appearance.19 In both acute and chronic ICD, the rash is sharply circumscribed and defined by the area of contact.8 Histologically, acute ICD shows spongiosis, epidermal bullae or vesicles, edema, and keratinocyte necrosis. Microscopically, chronic ICD has hyperkeratosis, parakeratosis, acanthosis, and hypergranulosis.20 Of note, histopathology cannot be used to distinguish ACD and ICD.21
The differential diagnosis of ICD includes ACD, eczema, psoriasis, tinea, and scabies. Scabies frequently affects the hands but usually presents with intense pruritus, which is less common in ICD. Psoriasis and chronic ICD can appear very similar on physical examination, but the characteristic presence of nail changes or plaques on the elbows and knees points toward psoriasis.
Diagnosing ICD depends mostly on detecting localized dermatitis on physical examination, which is supported by an in-depth history revealing exposure to an irritant. Given the similar appearance and histology of ACD, ruling out ACD with the use of patch testing is commonly performed.19 Although CD and ACD can coexist, this is rare and happens most frequently in occupations involving wet work.22 When there is concern for other skin pathologies, skin biopsy can be useful, and a potassium hydroxide prep can rule out fungal infection.
The most critical component of ICD treatment is irritant avoidance. For those with work exposures, using plastic instead of rubber gloves and adding cotton liners under gloves can aid in sweat absorption. In addition, thoroughly drying hands after washing can reduce the damaging effects of water on the skin barrier. Additional therapy includes topical corticosteroids to reduce inflammation, as well as emollients, moisturizers, or barrier creams. These creams restore the skin barrier and should be applied multiple times a day for optimal efficacy.5 At our patient’s next visit, he brought the gas mask he was required to wear. It was noted that the mask was coming in contact with his face in the areas of irritant contact dermatitis. On further questioning, the patient noted that he was cleaning his gas mask daily with harsh chemicals (required to potentially remove toxic gas residue). The patient was advised to wash off the mask a second time in order to remove the harsh cleaning chemicals used during cleaning. This led to resolution of his ICD.
Jessica C. Sheu, BA, and Michelle E. Lee, BA, are medical students at Baylor College of Medicine in Houston, Texas. Christopher Rizk, MD, is a dermatologist with Elite Dermatology in Houston, Texas.
References
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