Dyshidrotic Eczema (Pompholyx)

Dyshidrotic eczema, also known as pompholyx, is a chronic, recurrent, and often itchy skin condition that typically affects the palms of the hands, the sides of the fingers, and the soles of the feet. It is characterised by the appearance of small, deep-seated fluid-filled vesicles, usually measuring between 1 to 2 mm. These vesicles typically resolve within a few weeks, leaving behind scaling. The condition is often symmetric, affecting both sides of the body simultaneously.

While there is ongoing debate regarding the precise terminology and definitions of dyshidrotic eczema, the condition is also known by other names, including acute and recurrent vesicular hand dermatitis, acute palmoplantar eczema, vesicular endogenous eczema, and cheiropompholyx (affecting the hands). When it affects the feet, it is referred to as podopompholyx or pedopompholyx. In some cases, both the hands and feet are affected, known as cheiropodopompholyx.

The exact prevalence of dyshidrotic eczema remains unknown, though it is considered uncommon. Around 20% of patients receiving patch testing for hand dermatitis are diagnosed with dyshidrotic eczema. The condition does not show any significant correlation with age or gender, suggesting that it can affect anyone, regardless of demographic factors.

The precise cause of dyshidrotic eczema is still unknown. Early theories linked the condition to the blockage of sweat glands, but this theory has since been debunked. However, several factors have been associated with the disorder, including:

• Atopy: While some studies suggest a link between atopy (a genetic tendency to develop allergic diseases) and dyshidrotic eczema, the evidence is mixed.
• Contact Dermatitis: Both allergic contact dermatitis (particularly to allergens like nickel, chromium, and cobalt) and irritant contact dermatitis can exacerbate the condition.
• Fungal Infections: Tinea pedis (athlete's foot) is sometimes associated with a dyshidrotic-like eruption.
• Photoinduction: Ultraviolet A (UVA) exposure has been linked to triggering the condition.
• Immunoglobulin Therapy: Certain treatments involving immunoglobulin therapy may be associated with dyshidrotic eczema.
• Hyperhidrosis (excessive sweating): Excessive sweating is an aggravating factor for many patients.
• Other Factors: Seasonal changes, smoking, the use of oral contraceptives, and aspirin have been noted to contribute to flare-ups of dyshidrotic eczema.

Dyshidrotic eczema is a chronic, recurrent condition that presents as small, fluid-filled vesicles primarily on the sides of the fingers, palms of the hands, and soles of the feet. These vesicles are typically 1 to 2 mm in size, often symmetrical, and lack associated erythema (redness). In some cases, the vesicles may coalesce to form larger blisters. A hallmark of this condition is the intense itching it provokes. After 2 to 3 weeks, the vesicles usually resolve, leaving the skin to peel.

In individuals with darker skin types, dyshidrotic eczema may take on a tapioca-like appearance, emphasising the contrast between the colour of the vesicles and the surrounding skin.

Complications can arise from dyshidrotic eczema if it is left untreated or inadequately managed. Common complications include:

• Secondary Infections: Bacterial infections, particularly with Staphylococcus aureus or Streptococcus pyogenes, can lead to conditions like lymphangitis or cellulitis.
• Paronychia and Nail Dystrophy: If the eczema affects the areas near or around the nail fold, it can result in painful nail conditions.
• Physical and Psychological Disability: Dyshidrotic eczema can have a significant impact on an individual's quality of life, potentially leading to work absenteeism and economic consequences.

Diagnosis is typically made based on clinical history and physical examination, as the characteristic appearance of the vesicles makes the condition easily identifiable once other causes are excluded.

• Fungal Infection: Unilateral involvement may raise suspicion of a fungal infection like tinea manuum or tinea pedis, in which case skin scrapings should be taken for mycological analysis.
• Patch Testing: Patch testing may be necessary in chronic or atypical cases where an allergic contact cause is suspected.
• Skin Biopsy: Although rarely required, a skin biopsy will show spongiotic eczema.

When diagnosing dyshidrotic eczema, other conditions that present with similar symptoms should be considered, including palmoplantar pustular psoriasis, irritant or allergic contact dermatitis, tinea manuum or tinea pedis (fungal infections), scabies, or bullous pemphigoid.

Effective management of dyshidrotic eczema involves both general and specific treatment strategies aimed at controlling flare-ups and alleviating symptoms.

General measures include avoiding aggravating factors. Identifying and avoiding known triggers, such as allergens or irritants, is essential. Potassium permanganate soaks can be beneficial during the acute phase to reduce blistering.

Specific treatments include the use of topical treatments. Potent or ultrapotent topical steroids are commonly prescribed, alongside non-steroidal treatments like pimecrolimus, tacrolimus, or bexarotene gel. Regular use of emollients and moisturisers is crucial for maintaining skin hydration. Treatments for hyperhidrosis, such as iontophoresis or botulinum toxin, may also be indicated. Antifungal treatments are recommended if fungal infections are documented, and appropriate antifungal medications should be used. Phototherapy, such as topical psoralens combined with ultraviolet light A (tPUVA), may be beneficial for more resistant cases.

For severe or widespread dyshidrotic eczema, systemic treatments may be necessary. These include antihistamines, oral corticosteroids, or antibiotics or antifungals if secondary infections are present. Second-line therapies such as methotrexate, ciclosporin, azathioprine, or mycophenolate may be considered. In some cases, oral retinoids or biologic agents like dupilumab are prescribed.

Dyshidrotic eczema can be a chronic and cyclic condition. While some individuals may require long-term or second-line treatment, others may find that symptoms eventually settle over time, allowing treatments to be gradually withdrawn. However, the nature of the disorder is unpredictable, and ongoing management may be necessary for some patients.

While dyshidrotic eczema can be a challenging condition due to its chronic nature and recurrent flare-ups, early diagnosis and appropriate treatment can significantly improve patient outcomes. Through the use of topical treatments, lifestyle modifications, and systemic therapies when necessary, symptoms can be effectively managed and a higher quality of life maintained.