Contact Dermatitis: Irritant

ICD: Definition & Pathophysiology - Skin's Angry Reaction

• Definition: Non-allergic skin inflammation from direct chemical/physical injury.
• Epidemiology: Most common contact dermatitis (≈80% cases); major occupational hazard in India (e.g., wet work, chemicals).
• Pathophysiology:
  • Direct cytotoxic effect on keratinocytes.
  • Non-immunological, dose-dependent reaction.
  • Skin barrier disruption (lipid lamellae, proteins).
  • Innate immune activation (release of cytokines, chemokines).

⭐ ICD is a non-allergic inflammatory reaction of the skin caused by direct injury from an offending agent, accounting for approximately 80% of all contact dermatitis cases.

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ICD: Etiology & Risk Factors - Trouble Makers List

Common Irritants:

• Host Factors:
  • Atopy (eczema)
  • Age (extremes: very young, elderly)
  • Site (thin skin, e.g., eyelids; occluded areas)
• Environmental/Occupational Factors:
  • Occupation (healthcare, cleaning, construction, hairdressing)
  • Climate (low humidity, cold weather)

⭐ Chronic exposure to 'wet work,' involving frequent hand washing or prolonged contact with water, is a major occupational risk factor for developing irritant hand dermatitis.

ICD: Clinical Features - Skin's SOS Signals

⭐ In acute ICD, symptoms like burning and stinging often predominate over itching, which is more characteristic of allergic contact dermatitis (ACD).

ICD: Diagnosis & Differentials - Spotting the Irritant

• Diagnostic Approach:
  • History: Crucial. Identify potential irritants, exposure (duration, concentration, occlusion).
  • Clinical Exam: Erythema, edema, vesicles (acute); scaling, lichenification, fissures (chronic). Often well-demarcated.
• Patch Testing:
  • Primarily to exclude concomitant Allergic Contact Dermatitis (ACD).
  • Typically negative to allergens in pure ICD.

⭐ Patch testing in suspected ICD is primarily performed to exclude an overlapping allergic contact dermatitis, as pure ICD will yield negative patch test results to allergens.

• Key Differentials: ACD, atopic dermatitis, seborrheic dermatitis, psoriasis, tinea.

ICD: Management & Prevention - Soothe & Shield Plan

• Main Goals: Alleviate symptoms, resolve dermatitis, prevent recurrence.
• Core Strategies:
  • Irritant Identification & Avoidance: Paramount for resolution.
  • Skin Barrier Restoration: Emollients (liberal, frequent use), barrier creams, gentle cleansing.
  • Pharmacological Therapy:
    • Topical Corticosteroids (TCS): Potency tailored to site; e.g., medium potency (e.g., triamcinolone 0.1%) for trunk/limbs, low potency (e.g., hydrocortisone 1%) for face/flexures. Short-term use for acute flares.
    • Topical Calcineurin Inhibitors (TCIs): Off-label option, especially for sensitive areas or long-term intermittent use.
    • Systemic Therapy: Oral corticosteroids or immunosuppressants for severe, widespread cases.
• Preventive Measures:
  • Patient education on irritants and skin care.
  • Use of appropriate personal protective equipment (PPE).

⭐ The cornerstone of managing irritant contact dermatitis is the identification and complete avoidance of the causative irritant, coupled with diligent skin barrier repair using emollients.

High‑Yield Points - ⚡ Biggest Takeaways

• Non-immunologic inflammation from direct cytotoxic effect; no prior sensitization required.
• Most common contact dermatitis, more prevalent than allergic type.
• Acute: erythema, vesicles, bullae, burning, stinging. Chronic: scaling, lichenification, fissures.
• Lesions are sharply demarcated, typically on exposed areas (e.g., hands).
• Patch test is negative, differentiating from Allergic Contact Dermatitis (ACD).
• Management: irritant avoidance, emollients, and topical corticosteroids.
• Common irritants: soaps, detergents, solvents, acids, alkalis, chronic wet work.