Contact dermatitis (CD) is an eczematous reaction of the skin triggered by exogenous agents via two principal mechanisms: irritant contact dermatitis (ICD) due to direct cytotoxicity, and allergic contact dermatitis (ACD) mediated by type IV delayed hypersensitivity. CD is common, impacts occupational health, and frequently overlaps with atopic dermatitis. Diagnosis relies on clinical context and patch testing for suspected ACD. Management centers on avoidance, barrier repair, and anti-inflammatory therapy; workplace interventions are crucial for occupational cases.
Epidemiology
- One of the most common occupational skin diseases.
- ICD accounts for the majority of occupational cases (wet work, detergents, solvents, cutting oils).
- ACD prevalence varies by allergen exposure; common sensitizers include nickel, fragrance mix, methylisothiazolinone (MI/MCI), rubber accelerators, acrylates, hair dye (PPD), and preservatives.
Pathophysiology
- ICD: cumulative or acute disruption of stratum corneum with cytokine-mediated inflammation.
- ACD: hapten penetration, antigen presentation (Langerhans cells), clonal T-cell expansion; elicitation upon re-exposure.
- Risk factors: atopic skin barrier dysfunction (predisposes particularly to ICD), high-intensity exposures, occlusion, heat/humidity.
Clinical Features
- ICD: burning/stinging > itch, dry fissured hands, glazed/erythematous plaques; distribution matches exposure.
- ACD: pruritic, eczematous, sometimes vesicular plaques; may spread beyond contact site; classic patterns (eyelid dermatitis from airborne/fragrances, hand dermatitis, facial dermatitis from cosmetics).
- Chronicity leads to lichenification, hyperkeratosis, and fissuring.
Diagnosis
- Full exposure history: occupation, hobbies, cosmetics, personal care, topical medications, adhesives, gloves, hair/nail products.
- Patch testing: gold standard for ACD. Start with standardized baseline series (e.g., NACDG, European Baseline Series) and add occupation/hobby-specific allergens.
- Consider photo-patch testing when photosensitivity suspected (e.g., sunscreens, fragrances).
- Rule out tinea, psoriasis, atopic dermatitis flare, scabies in the differential.
Management
- Allergen/irritant identification and avoidance
- Post–patch test counseling with written lists of safe products (e.g., via databases/apps keyed to allergens).
- Occupational interventions: substitution of products, closed systems, protective equipment, task rotation, hand care protocols.
- Barrier repair and protection
- Emollients (fragrance-free, heavy-duty hand creams/ointments).
- Protective gloves matched to chemical (nitrile vs latex vs neoprene; avoid accelerators if sensitized); cotton liners to reduce occlusion dermatitis.
- Gentle hand hygiene: lukewarm water, mild cleansers; avoid overuse of alcohol rubs in fissured skin.
- Anti-inflammatory therapy
- Topical corticosteroids by site and potency; short bursts for flares, step-down to maintenance.
- Topical calcineurin inhibitors for face/eyelids or chronic sites.
- Severe/recalcitrant: short course systemic corticosteroids for acute severe ACD (e.g., poison ivy), or phototherapy/systemic immunomodulators in chronic occupational cases.
- Education and prevention
- Product label literacy; nickel test kits for metals; fragrance-free routines; avoid leave-on products with MI/MCI when sensitized.
- Workplace skin protection training.
Special Situations
- Eyelid ACD: common sensitizers include fragrances, nail cosmetics (transfer), ophthalmic preparations, hair dyes, topical antibiotics.
- Acrylate ACD: nail salons, dental/medical adhesives—use appropriate PPE and ventilation.
- Rubber accelerator ACD: switch to accelerator-free nitrile gloves.
References (recent guidelines and key reviews)
- AAD Guidelines/Practice Statements on Contact Dermatitis and Patch Testing, 2022–2024.
- European Society of Contact Dermatitis (ESCD) Guidelines on ACD Diagnosis and Management, 2023.
- NACDG/EADV consensus on baseline series updates, 2023–2024.
- Occupational dermatology consensus statements, 2022–2024.