Dyshidrotic eczema (otherwise known as pompholyx or vesicular eczema of the hands and/or feet.) is viewed by some dermatologists as a specific disease, while others use the term to describe a clinical picture that can have more than one cause. In the rest of this article I will take the view that Dyshidrotic eczema is a clinical reaction pattern caused by more than one condition.
The typical areas affected by Dyshidrotic eczema are the sides of the fingers and toes. On occasion any palmar area of the hand (palm-side) or plantar area of the feet (sole-side) can be affected. The hands are affected in isolation in 80% of cases, the feet in 10% of cases and both the hands and feet in the remaining 10% of cases. Dyshidrotic eczema can be extremely itchy.
The eruption consists of multiple small (<5mm) vesicles (small blisters) that are closely packed together. The vesicles are situated in the upper layer of the skin called the epidermis and are filled with a watery fluid. In severe cases these small vesicles coalesce with the resulting formation of large tense bullae (large blisters).
The causes of “Dyshidrotic eczema”:
- Dyshidrotic eczema (as a specific disease entity with an unknown cause)
- Atopic dermatitis
- Allergic contact dermatitis to many substances, including nickel
- Irritant dermatitis
- Id reaction (eczema due to an infection at a distant site e.g. the feet or scalp)
- Stress, although stress might just be contributing to one of the above factors
So, as you can see, there are quite a few potential causes of Dyshidrotic eczema. The first step is to identify which one of these diseases are the cause of the Dyshidrotic eczema. The diagnosis of Dyshidrotic eczema (as a specific disease entity with an unknown cause) is only made once other possible causes have been excluded.
You can be tested for Allergic contact dermatitis by patch testing. Patch testing involves placing many different substances on the back for 2 
days and then after 2 days the substances are removed and your skin is inspected. If you have an allergy to any of the substances that was patched on your back the area will be inflamed.
Id reactions are eczematous reactions occurring as a result of a fungal or bacterial infection elsewhere on your skin. It is important to remember that the infection does not have to be near the eczema. Infection of the feet or scalp can give rise to an Id reaction of the hands! Fungal infections of the feet has been reported in up to 30% of cases of Dyshidrotic eczema. In these case the treatment of the Dyshidrotic eczema will therefore be the treatment of the fungal infection of the feet. Be warned however, that even if you have a fungal infection of your feet, it is not necessarily the cause of your Dyshidrotic eczema!
When irritant dermatitis is the causative factor of your Dyshidrotic eczema it implies that your hands or feet are excessively exposed to a skin irritant such as soap or washing powder.
The primary treatment of Dyshidrotic eczema is therefore the “removal” of the cause. If the cause can not be identified the treatment is symptomatic.
Dyshidrotic eczema is mostly treated with potent topical corticosteroids combined with the frequent application of moisturizers. Other treatment options include light therapy (PUVA). In severe cases oral prednisolone can be used in short courses. In the most severe and resistant cases other immunosuppressants like Azathioprine, Methotrexate and even Cyclosporine have been used.