What treatment is recommended for a patient with dermatitis on the tops of both feet, possibly exacerbated by cold temperatures, who also has controlled eczema (atopic dermatitis)?

Treatment of Dermatitis on the Tops of Both Feet in a Patient with Controlled Eczema

Start with liberal emollients and a potent topical corticosteroid applied twice daily to the affected areas on the tops of the feet, while simultaneously investigating for allergic contact dermatitis through patch testing, as this atypical distribution (dorsal feet rather than flexures) strongly suggests contact allergy rather than typical atopic dermatitis flare. 1

Immediate Treatment Approach

First-Line Topical Therapy

• Apply a potent topical corticosteroid twice daily to the dermatitis on the tops of the feet, as this is the mainstay of treatment for eczematous conditions 2, 3
• Use the least potent preparation that achieves control, but given the location (dorsal feet with thicker skin), potent corticosteroids are appropriate and safer than on thin-skinned areas 2, 3
• Continue liberal emollient use throughout the day, applying immediately after bathing to create a lipid barrier that prevents water loss 2, 3
• Use soap-free cleansers and avoid alcohol-containing products 2

Cold Protection Measures

• Since the patient attributes symptoms to cold exposure, recommend protective footwear and warm socks to minimize cold-induced irritation 4
• Apply emollients more frequently during cold weather, as this can reduce flare rates by 60% 3

Critical Diagnostic Consideration: Rule Out Contact Dermatitis

This is the most important step given the atypical location. The dorsal feet distribution is highly suspicious for allergic contact dermatitis rather than typical atopic dermatitis, which predominantly affects flexural areas 1.

When to Suspect Contact Dermatitis

• Atypical distribution for atopic dermatitis (sides or tops of feet rather than flexures) 1
• Disease on the dorsal hands and fingertips or feet suggests contact exposure 1
• Worsening despite standard atopic dermatitis therapy 1
• New onset or significant worsening of previously controlled disease 1

Patch Testing Indications

• Strongly recommend patch testing for this patient given the unusual distribution on the tops of both feet 1
• Common allergens in atopic dermatitis patients include nickel, neomycin, fragrance, formaldehyde, preservatives, lanolin, and rubber chemicals 1
• Footwear components (rubber chemicals, leather tanning agents, adhesives) are particularly relevant for foot dermatitis 1, 5
• Patch testing involves applying suspected allergens to unaffected skin for 48 hours, with assessment at removal and again up to 7 days later for delayed reactions 1

Managing Secondary Infection

Recognition and Treatment

• Watch for increased crusting, weeping, or pustules indicating bacterial superinfection 2, 3
• Start oral flucloxacillin immediately if infection is suspected, as Staphylococcus aureus is the most common pathogen 2, 3
• Continue topical corticosteroids during infection when appropriate systemic antibiotics are given concurrently—do not withhold steroids 2, 3
• If grouped vesicles, punched-out erosions, or sudden deterioration with fever occur, suspect eczema herpeticum and initiate oral acyclovir immediately 2

Escalation Strategy if First-Line Fails

After 4 Weeks of Inadequate Response

• Consider topical calcineurin inhibitors (tacrolimus 0.1% ointment) as an alternative, which has shown efficacy for hand and foot eczema 6
• Refer for phototherapy (narrowband UVB 312 nm) if topical therapy fails after 4 weeks 2
• Consider systemic immunomodulatory agents (cyclosporine, azathioprine, methotrexate, or dupilumab) only after optimizing topical therapy and considering phototherapy 1, 3

Common Pitfalls to Avoid

• Do not assume this is simply an atopic dermatitis flare without investigating contact allergy—the dorsal foot location is atypical and demands patch testing 1
• Do not withhold topical corticosteroids when infection is present; they remain primary treatment when antibiotics are given 2, 3
• Avoid undertreating due to steroid phobia—explain that appropriate short-term use of potent steroids on the feet is safer than chronic undertreated inflammation 3
• Do not use systemic corticosteroids except for acute severe flares requiring rapid control, and never for maintenance 2

Patient Education Points

• Explain that the foot location suggests possible contact allergy to footwear materials, not just cold exposure 1, 5
• Emphasize that emollients should be continued even when skin appears clear, as this prevents future flares 2, 3
• Clarify that topical corticosteroids on the feet are safe when used appropriately, as this area has thicker skin with lower risk of atrophy 2, 3