1.1.2.7 Dyshidrotic Dermatitis

It is a chronic, intermittent, highly pruritic vesicular sometimes even bullous eruption with faint erythema that involve hands (palms, lateral aspects of fingers) and feet (soles) and has characteristics of an eczema.

It represents an eczematous vesicular reaction pattern involving the hands and/or feet and is mostly secondary to a variety of stimuli. Idiopathic, allergic or non-allergic contact reactions, atopic dermatitis, eczematous reaction to distal infections such as tinea (then known as an id reaction) or bacterial infections are common causes. It is occasionally related to triggers such as contact irritants and even metal hypersensitivity. Dyshidrotic eczema of the hands is more frequently observed in patients sensitized to nickel sulphate. Sometimes a nickel-rich diet could cause clinical flares via the systemic route.

No clear-cut connection with sweat gland activity or malfunction exists. Therefore, the (historical) term dyshidrosis may be misleading.

The tiny pruritic, clear fluid-filled vesicles on palms and soles arise on the lateral and palmar surfaces of the fingers and the lateral sides of the toes. Sometimes, the vesicles can remain very discrete and dry quickly (small yellowish-brown scales), with a centrifugal desquamation. In other cases, vesicles become confluent, multilocular, sometimes haemorrhagic, with bullae formation and oozing (bullous dyshidrosis or cheiro-podo pompholyx).

The appearance of vesicles is usually accompanied by strong pruritus, which leads to secondary scratching. Deep and painful fissures can accompany dyshidrotic eczema. Sometimes the eruption may evolve into a chronic hand eczema.

Hands and feet, palmar and lateral areas of the fingers and toes, and also soles and palms. The lesions may spread to the back of the fingers, backs of hands, wrists, back of feet, ankles.

According to the course it may be acute or subacute or chronic with vesicular flares. Depending on the causes underlying one can further subtype into idiopathic subtypes or secondary forms to contact allergy, atopy, or reactions to infections such as tinea (then known as an “id” reaction).

Dyshidrosis lamellosa sicca, also known as keratolysis exfoliativa (KE), or focal palmar peeling syndrome is considered a subtype of dyshidrotic eczema and characterized by superficial dry blister roofs and collarette desquamation manifesting as non-inflammatory irregular circumscribed annular or circinated patches on the palms and soles. It is typically observed in young patients sometimes with an atopic background that complain of recurrent asymptomatic peeling on the palms (and occasionally the soles).

Where distant mycological or bacterial infection is suspected, microbiological cultures may be useful. Patch test to rule out an associated allergic contact dermatitis. Measurement of IgE may also be helpful to rule out atopic dermatitis.

Intraepidermal spongiotic vesicles mostly close to the acrosyringeal orifices. Congestion of the dermal sweat gland duct with secretion of sweat and sweat enriched inflammatory substances or specific IgE (atopics) in the surrounding dermis leading to severe itching. The image of the dyshidrotic vesicles is that of eczema with large spongiotic vesicles and discrete or severe dermal perivascular and periductal inflammatory infiltrate.

The course depends on the cause. Idiopathic dyshidrosis is sometimes relapsing and seasonal (crisis of spring and autumn) and sometimes non-seasonal. Idiopathic and atopic forms are often chronic and recurrent.

When dyshidrosis becomes chronic, secondary infection may develop. It may lead to promotion of allergic contact dermatitis.

The clinical features are typical and characteristic. To distinguish it from atopy-associated hand dermatitis one has to look for atopic stigmata. Patch testing is useful to exclude allergic contact dermatitis. A possible relationship between dyshidrotic eczema and a positive nickel test has to be ruled out. Dyshidrosis may be aggravated by oral nickel intake.

Clinical and mycological examination of the feet in the interdigital folds may be useful to determine an associated tinea pedis in cases of dyshidrotic eczema as an “id” reaction, i.e. eczematous vesicular eruptions secondary to distant bacterial or mycotic infections.

A variety of differential diagnoses include tinea pedis, early stages of palmoplantar pustulosis, pustular psoriasis, atopic dermatitis, allergic contact dermatitis and localized bullous pemphigoid. Hyperhidrosis associated to humidity and higher temperatures my produce hidrotic vesicles at the lateral finger sites.

Avoidance of working in humid areas and professions with constant washing of vegetables or glasses (kitchen, restaurant) and wearing of occlusive gloves. Avoid overwashing of hands because of barrier destruction and changes of microbiota.

Topical galenics: no ointment because of exaggerating occlusion, drying with solution or paste based galenics. Wet dressings with antiseptic solutions are essential. Topical corticosteroids in non- alcoholic galenic form (painful) such a milk/solution or paste are useful. Topical calcineurin antagonists in a lotion or cream may also be helpful. On occasions a short course of systemic corticosteroids can efficiently suppress the acute flare. Antihistamines are recommended in cases of intense pruritus.

First clinical trials with a biologic and JAK inhibitors with effects on the course and severity of disease with systemic dupilumab, tralokinumab, upadacitinib or topical delgocitinib are promising.