Definition
- Any skin disorder brought about by contact with an exogenous substance that triggers an allergic and/or irritant response
Signs and Symptoms
Allergic Contact Dermatitis (ACD)
- Initially, lesions appear on the cutaneous site of principal exposure; may spread to other more distant sites due to contact or autosensitization
- Lesions are typically asymmetrical, ill-defined and unilateral
- Specific signs and symptoms will depend on the duration, location, degree of sensitivity and concentration of allergens
- Patch test shows reaction to allergen
- Acute eruptions present with macular erythema, papules, vesicles and bullae
- Lesions are usually lichenified, scaling, fissures with or without vesicles
- Pigmentary changes can occur
Other Types of ACD
- Airborne contact dermatitis is caused by an airborne transmission of contact allergen commonly seen in the face and neckline
- Hematogenous contact dermatitis is a special form of ACD which is triggered after epicutaneous sensitization to allergens and commonly seen in the intertriginous areas and gluteal regions
- Photoallergic contact dermatitis is triggered by combined exposure to photosensitizers and ultraviolet (UV) light
- Phototoxic contact dermatitis is seen in sun-exposed skin and lesions with well-defined border
- Protein contact dermatitis is a less common type caused by immunoglobulin E (IgE)-mediated allergy
- Prone to irritation from chemical substances are the face, dorsum of the hands, finger webs, palms, soles or back
- Lesions are usually sharply defined at contact sites
- Acute lesions are painful, edematous, erythematous, weepy and vesicular
- There is associated sensation of burning, stinging or pain in the site of contact to irritant
- Usually results from a single exposure to an irritant or caustic chemical
- Chronic lesions are dry, erythematous, scaling, fissuring, cracked and lichenified
- Hardening and adaptation of the skin may occur due to repeated contact with irritants
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Common Trigger Factors
- ACD: Medications, certain plants, metals, foods, fragrances, stabilizers in skin products, preservatives, etc
- ICD: Strong alkaline soaps, organic solvents, acid, chlorinated or bleach type ingredients, inhalants, airborne chemicals, etc
- Location of inflammation may suggest trigger factors
- Eg scalp and ears
- Possible trigger factors: Shampoo, hair dyes, topical medication, spectacles, metal earrings, etc
- Eg scalp and ears
ACD and ICD Related to Occupational Exposure
- Exposure to cement, epoxy, glues, paint and solvents may trigger ACD
- Fuels, lubricants and cement may trigger ICD