What is the most likely diagnosis and recommended management for a 55‑year‑old male with a bilateral itchy rash in the axillae and legs that has not improved with clotrimazole and who has a known wool allergy?

Most Likely Diagnosis: Allergic Contact Dermatitis

The most likely diagnosis is allergic contact dermatitis, not a fungal infection, given the bilateral distribution in the axillae and legs, failure to respond to clotrimazole, and known wool allergy—this patient requires patch testing and immediate avoidance of suspected allergens, particularly wool-containing garments. 1, 2

Why This Is Not a Fungal Infection

• Fungal infections (tinea) typically present with annular papulosquamous lesions rather than eczematous changes, and they rarely occur bilaterally in both axillae and legs simultaneously 3
• The failure to improve with clotrimazole after adequate treatment strongly suggests this is not a dermatophyte infection—fungal infections should show some response to appropriate antifungal therapy 1
• The bilateral, symmetrical distribution in axillae and legs is highly characteristic of contact dermatitis from clothing or fabric allergens, not fungal infection 2, 4

Key Clinical Features Supporting Contact Dermatitis

• The known wool allergy is a critical clue—wool is a well-recognized contact allergen that commonly causes dermatitis in areas where clothing contacts skin (axillae, legs) 5, 2
• Pruritus is a hallmark feature of contact dermatitis, occurring in both irritant and allergic forms 2, 4
• The bilateral distribution in clothing-contact areas (axillae and legs) strongly suggests a fabric-related allergen rather than infection 2, 6
• Contact dermatitis presents as erythematous, eczematous lesions with visible borders, often with scaling, and can be clinically indistinguishable from other forms of eczema without patch testing 1, 2, 4

Immediate Management Steps

1. Complete Allergen Avoidance

• Immediately discontinue all wool-containing clothing and bedding—this is the single most important intervention 4, 6
• Replace wool garments with smooth cotton clothing to avoid further irritation 5
• Review all topical products, detergents, and fabric softeners for potential allergens 2, 6

2. Topical Corticosteroid Therapy

• Apply a moderate-to-high potency topical corticosteroid such as triamcinolone 0.1% or clobetasol 0.05% twice daily to affected areas 4
• For the axillae (a thinner-skinned intertriginous area), consider topical calcineurin inhibitors (tacrolimus 0.1% ointment or pimecrolimus 1% cream) to avoid steroid-induced atrophy 2
• Continue treatment for 2-4 weeks, then implement "steroid holidays" to minimize adverse effects 5

3. Adjunctive Barrier Restoration

• Apply fragrance-free emollients liberally immediately after bathing to restore barrier function 5, 2, 6
• Use soap-free cleansers instead of regular soaps that strip natural lipids 5, 2
• Keep fingernails short to reduce skin trauma from scratching 5

4. Symptomatic Relief for Pruritus

• Consider sedating antihistamines (hydroxyzine or diphenhydramine) at bedtime to improve nighttime itching through sedative effects 5
• Non-sedating antihistamines have no proven benefit in contact dermatitis and should not be used 5

Diagnostic Confirmation: Patch Testing

• Patch testing is the gold standard for confirming allergic contact dermatitis and identifying specific allergens 1, 2, 7
• Testing should be performed if the diagnosis remains uncertain or if symptoms persist despite avoidance of suspected allergens 1, 4
• The optimal timing for patch test readings is day 2 and day 4, with an additional reading at day 6-7 to capture 10% more positives 1
• Common allergens to test in this patient include wool, nickel, fragrances, preservatives, rubber accelerators, and potentially the clotrimazole itself (imidazole antimycotics can cause contact allergy) 1, 8

Critical Pitfalls to Avoid

• Do not continue antifungal therapy—this patient does not have a fungal infection, and prolonged use of topical antifungals can themselves cause allergic contact dermatitis 8
• Do not apply topical antibiotics routinely—neomycin and other topical antibiotics sensitize 5-15% of patients and increase resistance risk 2
• Do not assume this is atopic dermatitis without patch testing—contact dermatitis occurs in 6-60% of patients with atopic dermatitis and is clinically indistinguishable 3
• Do not use very potent corticosteroids continuously in the axillae without breaks—this thin-skinned area is prone to atrophy 5, 2

When to Refer

• Refer for patch testing if symptoms persist after 4 weeks of appropriate allergen avoidance and topical corticosteroid therapy 1, 5
• Consider dermatology consultation if the diagnosis remains uncertain or if systemic therapy is contemplated 5
• Occupational dermatology referral may be needed if work-related exposures are suspected 1

Expected Clinical Course

• With complete allergen avoidance and appropriate topical therapy, improvement should be visible within 1-2 weeks 4, 6
• If no improvement occurs, reconsider the diagnosis and ensure complete avoidance of all suspected contactants 2, 4
• Only 25% of occupational contact dermatitis cases achieve complete healing, with 50% having intermittent symptoms at 10 years—emphasizing the critical importance of early allergen identification and avoidance 2