What is the diagnosis and treatment for a 60-year-old female patient with light brown skin experiencing skin pigmentation and itching on the face, particularly in areas contacting a head scarf, which worsens with travel, wetness, and friction?

Diagnosis: Allergic Contact Dermatitis from Head Scarf

This patient has allergic contact dermatitis caused by friction and contact with her head scarf, exacerbated by moisture and mechanical irritation during travel. 1, 2

Clinical Reasoning

The presentation is classic for contact dermatitis with several key diagnostic features:

• Location-specific pigmentation in areas contacting the head scarf indicates an external trigger rather than systemic disease 1, 2
• Pruritus worsening with wetness suggests irritant or allergic contact dermatitis, as moisture disrupts the skin barrier and enhances allergen penetration 2, 3
• Exacerbation with friction during travel points to mechanical irritation combined with prolonged contact exposure 4
• Post-inflammatory hyperpigmentation is the likely cause of the brown discoloration, particularly common in patients with darker skin types after chronic inflammation 1, 5

The differential diagnosis would include vitiligo (but this causes depigmentation, not hyperpigmentation), melasma (but this doesn't correlate with head scarf contact or itching), and seborrheic dermatitis (but this typically has greasy yellowish scaling) 6, 7.

Treatment Algorithm

Step 1: Remove the Trigger

• Immediately discontinue use of the current head scarf or rotate to different materials to identify the causative allergen 6, 1
• Common culprits include fabric dyes, formaldehyde resins in synthetic fabrics, nickel in decorative elements, or rubber/elastic components 1, 2
• Switch to 100% cotton head scarves without dyes or decorative metal elements as a trial 6

Step 2: Acute Inflammation Management

• Apply mid- to high-potency topical corticosteroids such as triamcinolone 0.1% or clobetasol 0.05% twice daily to affected areas for 2-3 weeks 1
• If the affected area exceeds 20% of facial surface, consider a short course of oral prednisone tapered over 2-3 weeks to prevent rebound dermatitis 1
• Avoid rapid discontinuation of steroids as this can cause rebound inflammation 1

Step 3: Skin Barrier Restoration

• Apply emollients liberally 2-3 times daily, particularly oil-based preparations like almond oil, olive oil, or mineral oil to maintain skin hydration and prevent cracking 6
• Keep the affected area dry when possible, especially during travel 6, 7
• Use gentle, fragrance-free cleansers to avoid additional irritation 2

Step 4: Address Hyperpigmentation (After Inflammation Resolves)

• Do NOT use hydroquinone in this patient - she has light brown skin and the FDA warns that hydroquinone may produce exogenous ochronosis (gradual blue-black darkening), which occurs more frequently in Black patients but also in those with darker skin types 8
• Instead, focus on strict sun protection with broad-spectrum SPF 30+ sunscreen daily, as UV exposure will worsen post-inflammatory hyperpigmentation 8
• The pigmentation will gradually fade over 6-12 months once inflammation is controlled and sun protection is maintained 1

Step 5: Diagnostic Confirmation (If Treatment Fails)

• Perform patch testing if symptoms persist despite avoidance and treatment, to identify the specific allergen 1, 2
• Test for common textile allergens including formaldehyde resins, disperse dyes, nickel, and rubber accelerators 2, 3

Critical Pitfalls to Avoid

• Never use hydroquinone for post-inflammatory hyperpigmentation in patients with brown or darker skin due to risk of paradoxical darkening (ochronosis) 8
• Avoid neomycin-containing topical antibiotics as 5-15% of patients with chronic dermatitis develop hypersensitivity reactions 6, 7
• Do not prescribe short steroid courses (less than 2 weeks) for extensive contact dermatitis, as rapid discontinuation causes rebound 1
• Ensure complete avoidance of the trigger - partial avoidance will lead to persistent low-grade inflammation and continued pigmentation 1, 2

Maintenance and Prevention

• Continue emollient use indefinitely to maintain skin barrier function 6, 2
• Wear only cotton or silk head scarves without synthetic dyes or metal decorations 1
• Keep a spare cotton head scarf for travel to change if the primary one becomes wet 6
• Apply topical corticosteroids intermittently (2-3 times weekly) if mild inflammation recurs 6