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Irritant and Allergic Contact Dermatitis, Occupational Dermatoses, and Dermatoses Due to Plants


Key Points

  • Irritant contact dermatitis (ICD)

    • –

      Accounts for 80% of all causes of contact dermatitis

    • –

      Secondary to a local toxic effect caused by a topical substance or physical insult

  • Allergic contact dermatitis (ACD)

    • –

      Accounts for 20% of all causes of contact dermatitis

    • –

      A delayed-type hypersensitivity reaction to a substance to which the individual has been previously sensitized

    • –

      Compared to ICD, more commonly presents with pruritus during the acute phase

  • One of the most common occupational dermatoses is ICD.

  • Plants can cause a variety of skin reactions, the most common in North America being ACD to poison ivy.

Irritant Contact Dermatitis

  • Localized, non-immunologically mediated cutaneous inflammatory reaction ( Figs 12.1–12.5 ).

    Fig. 12.1, Bilateral irritant contact dermatitis of the feet and ankles due to chronic occlusive footwear.

    Fig. 12.2, Bilateral irritant contact dermatitis of the palms secondary to repeated contact with paint solvents.

    Fig. 12.3, Moderately severe irritant contact dermatitis of the hands due to chronic exposure to disinfecting solutions and antiseptics.

    Fig. 12.4, Chemical burn from topical application of apple cider vinegar mimicking child abuse in an infant.

    Fig. 12.5, Cheilitis due to irritant versus allergic contact dermatitis. A Irritant contact dermatitis – this patient had the habit of licking his lips and there is involvement of the vermilion and cutaneous lips as well as the perioral region. B Allergic contact dermatitis to oxybenzone with involvement of the upper and lower lips.

  • Secondary to a direct toxic effect

    • –

      Chronic – erythema, fissures, and scale which is oftentimes thick

    • –

      Acute – erythema, edema, and vesiculation followed by erosions and scaling; in severe cases may lead to epidermal necrosis (a “chemical burn”)

  • Commonly affects the hands (see Fig. 13.1 ); Table 12.1 reviews pertinent questions for when environmental exposures are suspected.

    Table 12.1
    Points to consider when evaluating hand dermatitis and environmental exposures are suspected.
    Courtesy, Peter S. Friedmann, MD.
    Occupation Are findings consistent with work exposure as a cause?
    Does time off result in improvement?
    Materials handled Do labels and material safety data sheets (MSDS) list potential irritants or allergens?
    Is there a relationship to handling food?
    Other persons in workplace affected?
    Protective equipment (e.g. gloves) used?
    Previous skin disease or history of atopy Is there a history of eczema as a child?
    Known allergies Is there unrecognized exposure?
    Treatment May cause allergic contact dermatitis
    Hobbies Including exposure to plants

  • A common cause of cheilitis (lip-licking; see Fig. 13.5 ).

  • May be secondary to an occupational exposure ( Table 12.2 )

    • –

      Common causes are soaps and wet work, and less often petroleum products, cutting oils, and coolants

    Table 12.2
    Common irritants and examples of major exposure(s).
    Courtesy, David Cohen, MD.
    Irritant Examples of major exposure(s)
    Inorganic acids
    Hydrofluoric acid Etching of glass/metal/stone; rust/stain/limescale removers
    Sulfuric acid Manufacturing of fertilizers, textile fibers, explosives, paper
    Hydrochloric acid Production of fertilizers, dyes, paints; used in food processing
    Chromic acid Used in metal treatments
    Nitric acid Production of fertilizers and explosives; in cleaning products
    Phosphoric acid Used in fertilizer, pharmaceuticals, water treatment
    Organic acids
    Formic acid Used as a neutralizer in leather manufacturing
    Alkalis
    Sodium hydroxide Used in the manufacture of bleaches, dyes, vitamins, pulp, paper, plastics, soaps and detergents
    Calcium oxide
    Metal salts
    Arsenic trioxide Aerosolized in the smelting of metals
    Beryllium compounds Used in the production of hard, corrosion-resistant alloys
    Solvents
    Stoddard solvent Used in dry cleaning
    Water Ubiquitous
    Alcohols
    Glycols Commonly used in cosmetic products
    Detergents and cleansers
    Sodium lauryl sulfate Detergents and cleansers
    Cocamidopropyl betaine Detergents, therapeutic formulations, personal care products
    Disinfectants
    Ethylene oxide Medical sterilization
    Chloroxylenol Baby powders and shampoos
    Iodines Surgical scrub, shampoo, skin cleansers
    Benzalkonium chloride Used for instrument cleansing; in ophthalmic solutions
    Food Pineapples, garlic, mustard
    Plants Thistles, prickly pears, grasses
    Plastics
    Bodily fluids
    Fabric/man-made vitreous fibers (e.g. fiberglass)

  • DDx: when severe, thermal burn; ACD and other dermatitides; there may be a combination of causes, e.g. ICD and ACD, ICD and atopic dermatitis.

  • Rx: primarily avoidance of the irritant.

Allergic Contact Dermatitis

  • In contrast to ICD, more commonly presents with pruritus during the acute phase; the chronic phase has significant overlap with ICD ( Fig. 12.6 ).

    Fig. 12.6, Allergic contact dermatitis to shoes – acute versus chronic.

  • Initially, well demarcated and localized to site of contact with the allergen ( Figs 12.7–12.12 ).

    • –

      Acute – in addition to erythema and edema, vesicobullae and weeping may develop ( Fig. 12.7 )

    • –

      Chronic – often lichenified with scale ( Figs 12.6B and 12.9 )

    Fig. 12.7, Acute vesiculobullous allergic contact dermatitis.

    Fig. 12.8, Acute allergic contact dermatitis with a prominent component of edema.

    Fig. 12.9, Chronic allergic contact dermatitis due to glutaraldehyde.

    Fig. 12.10, Allergic contact dermatitis to p -phenylenediamine in a temporary tattoo.

    Fig. 12.11, Airborne contact dermatitis.

    Fig. 12.12, Clinical manifestations of Anacardiaceae dermatitis.

  • Can have autosensitization with extension beyond original site (see Ch. 11 ); airborne allergens primarily contact exposed skin and can mimic (or overlap) photoallergic or phototoxic reactions ( Fig. 12.11 ).

  • Occasionally, there is a diffuse, patchy distribution, depending on the allergen (e.g. body wash or shampoo) and/or concomitant atopic dermatitis.

  • Common allergens are metals, fragrances, preservatives, and topical antibiotics, as well as plants, in particular poison ivy/oak (see below) ( Fig. 12.12 ).

  • Common causes of occupational ACD are rubber, nickel, epoxy resin, and aromatic amines.

  • Suspected allergens should be avoided; a repeat open application test can be tried first but patch testing is required for accurate diagnosis; detailed lists of allergen-containing products are available.

  • In patch testing, specific concentrations of allergens are dissolved in petrolatum or water and placed in wells that are then applied to the patient’s back for 48 hours ( Figs 12.13 and 12.14 ); grading of reactions is performed at two time points ( Table 12.3 ).

    Fig. 12.13, Placement of allergens to the patient’s back utilizing AllergEAZE™ chambers.

    Fig. 12.14, Sites of specific patch tests labelled for future reference following removal of the chambers.

    Table 12.3
    International grading system for patch tests.
    Grading is performed at two time points after the patch tests have been in place for 48 hours (then removed; see Fig. 12.14): initially after removal and then 1–7 days later.
    +/− Doubtful reaction, faint macular erythema
    + Weak, non-vesicular reaction with erythema, infiltration, and papules
    ++ Strong, vesicular reaction with infiltration and papules
    +++ Spreading bullous reaction
    − Negative reaction
    IR Irritant reaction

  • DDx: other forms of dermatitis (ICD, atopic dermatitis, stasis dermatitis, seborrheic dermatitis), erythematotelangiectatic rosacea, dermatophyte infection.

  • Rx: short term: topical and systemic CS depending on severity; long term: avoidance of allergen(s).

Common Allergens

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