What causes dyshidrotic eczema and how is it treated?

Causes and Treatment of Dyshidrotic Eczema

Dyshidrotic eczema is primarily caused by metal allergies, atopy, hyperhidrosis, and environmental factors, and is most effectively treated with emollients as daily maintenance and topical corticosteroids for flare-ups, with PUVA therapy being an effective second-line treatment for refractory cases. 1, 2

Causes of Dyshidrotic Eczema

Primary Causes

• Metal allergy is considered one of the important potential etiologic factors for dyshidrotic eczema, with improvement observed after removing metal allergens 2
• Atopy (genetic predisposition to allergic conditions) is associated with frequent relapses in patients with dyshidrotic eczema 3
• Hyperhidrosis (excessive sweating) can induce inflammatory reactions that contribute to dyshidrotic eczema 3
• Neurovegetative disturbances may play a role in recurrent cases 3

Secondary Causes

• Infectious agents (bacterial, fungal) can trigger dyshidrotic eczema 3
• Allergic reactions to environmental substances may precipitate flares 3
• Seasonal factors, particularly during spring allergy season, can exacerbate symptoms 2

Clinical Presentation

• Characterized by pruritic, small tense vesicles mainly on the palmoplantar region and lateral/ventral surfaces of the fingers 2
• Vesicles are embedded in the epidermis below the thick stratum corneum 3
• Vesicles can become distended and painful when they grow in size 3
• The condition typically resolves within three weeks but relapses are common 3

Treatment Approach

First-Line Treatments

• Emollients should be applied liberally and frequently to maintain skin hydration and improve barrier function 4
• Use soap substitutes (dispersible creams) instead of regular soaps and detergents which remove natural skin lipids 1, 4
• Bathing is beneficial for cleansing and hydrating the skin, with emollients most effective when applied immediately after bathing 1, 4
• Mild to moderate potency topical corticosteroids should be applied to affected areas during flares 4
• For hand eczema, oral PUVA has been shown to be superior to UVB in controlled studies 1

Second-Line Treatments

• Topical tacrolimus (FK506) 0.1% ointment is effective for dyshidrotic palmar eczema and offers an alternative for rotational therapy with corticosteroids in chronic cases 5
• PUVA therapy (psoralen plus UVA) has shown significant improvement in 58-81% of dyshidrotic eczema cases in uncontrolled studies 1
• Exposure to sunlight may be beneficial as adjuvant therapy due to the UVA1 radiation component, which can alleviate manifestations of dyshidrotic eczema 6

Treatment for Refractory Cases

• For severe cases unresponsive to conventional therapies, low-dose external beam radiation therapy has shown complete resolution with durable response 7
• Oral antihistamines may help manage pruritus during flares, primarily due to their sedative properties 4

Management of Complications

• Monitor for signs of secondary infection (crusting, weeping) 4
• If bacterial superinfection occurs, appropriate antibiotic treatment should be initiated 4
• For viral infections (particularly herpes simplex) presenting as grouped, punched-out erosions or vesicles, antiviral treatment may be necessary 8

Special Considerations

• Metal allergy testing should be considered in persistent cases, with removal of identified metal allergens potentially leading to improvement 2
• In cases with identified infectious or allergic triggers, treating the underlying cause may lead to resolution 3
• For maintenance therapy in chronic cases, consider a proactive approach using topical anti-inflammatories 2-3 times weekly on previously affected areas to reduce flare risk 4

Indications for Specialist Referral

• Diagnostic uncertainty 4
• Failure to respond to first-line treatments 4
• When considering second-line treatments such as PUVA or radiation therapy 4