Features - Pompholyx eczema by Mazin Al-Khafaji

Pompholyx eczema is a very distinctive form of eczema, characterised initially by an eruption of very itchy vesicles on the sides of the fingers and palms of the hands and occasionally the soles of the feet and toes. The vesicles, which contain clear fluid, usually subside without rupturing, although in some cases they may become tense, burst and discharge. In either case, the vesicular stage, which usually lasts for one to two weeks is followed by a dry desquamating phase, by which time the itching is usually markedly reduced.

This condition has been recognised and described in medical texts in China since at least the Ming dynasty. In the True Lineage of External Medicine, Chen Shi-gong uses the name River snail vesicle ( ), giving a fair description of the disorder: "River snail vesicle mostly erupts on the hands and feet, suddenly it is as if the area was on fire; purple, white and yellow vesicles will appear next; this is wind damp attacking and pouring into the Spleen channel.” Less than a century later, Gu Shi-deng the author of Collection of Treatments for Sores uses the alternative and more commonly used name of Ant nest ( ) to define it: "Ant nest"mostly erupts on the hands and feet, it’s appearance is like the nest of an ant, just like the pricks of a needle, the itching is extreme and enters the Heart. On rupturing there is a watery exudation " it may also erupt on the back of the hands and wrists”.

The name pompholyx is derived from the Greek word for the boss of a shield and by extension a bubble or blister, the characteristic lesion of this eczema. The alternative name dyshidrotic eczema refers to the common finding associated with this eczema of excessive sweating from the palms and occasionally the soles.

Lesions

Vesicle is the characteristic lesion of pompholyx eczema. The smaller vesicles are commoner, although they may coalesce to form larger vesicles or bullae. Typically the deep-set vesicles develop rapidly, and are accompanied by intense itching. Due to the thickness of the epidermis of the palms and soles, the fluid inside often appears pearly white, and instead of rupturing and discharging, as it would more often do if it were found elsewhere on the body, it is usually reabsorbed without a break in the skin.

Bullae may form as a result of several vesicles coalescing, and are more often seen on the feet. Occasionally they may grow to a size of several centimetres. In such cases pain and incapacity may be significant features.

Crusting is formed only if the vesicles or bullae rupture and discharge. There will typically be a mixture of yellow or white crusting tinged with dry bloody scabs.

Erosion occurs as a consequence of breakdown of a vesicle or bulla. The superficial layer of skin, the epidermis, is worn away exposing the lower layer of skin, the dermis. This is almost always associated with crusting.

Desquamation, scales and fissures are seen at the end stages of a cycle of eruption. They may develop following re-absorption, or after break down, discharge and crusting of the vesicles and bullae. In some chronic cases, only the fissures are seen, with absence of any vesicles.

Lichenification is most commonly seen in chronic cases, where typically the patient has suffered repeated attacks over many years, and vesicle formation is replaced by desquamation, fissuring and lichenification. Lichenification is often more readily observable when the eczema spreads to the dorsal aspect of the hands and fingers.

Pustules are not infrequently seen when the area becomes infected.

Distribution

Pompholyx eczema affects the hands and feet, either together or separately. By far the most common presentation, accounting for about 80% of cases is for the hands to be involved exclusively. The remaining 20% of cases will be equally divided amongst patients with involvement of either the feet alone, or the hands and feet together.

Being an endogenous condition, the eruptions are almost always symmetrical. Although an asymmetrical presentation may occur, the possibility of a fungal infection or a contact sensitivity should always then be considered. The vesicles tend to erupt on the sides of the fingers and palms, and often on the dorsal aspect of the distal fingers, where the skin is anatomically similar to that of the palms (absence of hair follicles). In more severe attacks the eczema spreads to the dorsum of the hands. If the eruption is particularly virulent, the eczema may extend upwards to involve the arms, neck and even the face. In a minority of cases, a generalised eczema of the entire body may also occur.

When the feet are involved, the same pattern will emerge as is seen on the fingers and palms, with an increased tendency for the vesicles to become confluent, and merge into bullae. As with the hands, in more persistent cases the eruption will affect the dorsal aspect of the feet, and may spread up the legs.

Natural history and clinical features

Pompholyx eczema is most often seen in 20-40 year olds, and only rarely in the elderly or prepubescent. It occurs slightly more frequently in females, and accounts for up to 20% of eczema cases seen in the clinic.

There are several factors that are regularly associated with initial eruptions, or subsequent relapses. Frequently the first attack is triggered by hot weather, appearing in late spring or summer; indeed a proportion of patients tend to get eruption only at these times, the eczema spontaneously subsiding once the weather turns cooler. Alternatively an initial attack, or exacerbation, may follow intense emotional upset, frustration, grief or unremitting stress. Commonly excessive hand washing in new mothers, or the use of detergents, or other chemicals without proper protection will be sufficient to irritate the hands and precipitate an attack.

The symmetrical outbreak of vesicles may either start on the inner aspects of the fingers, on the palms themselves, or in both areas at once. In mild cases only the sides of the fingers may be affected. The patient usually reports a prickly, burning hot sensation before the appearance of the vesicles, followed rapidly by intense itching once the vesicles emerge. The palms and the area between the fingers typically glisten with sweat, drawing attention to the common finding of excessive sweating from affected areas.

At the early stages, erythema is conspicuous by its absence, developing either only slightly as the condition develops, or more intensely only after it has progressed. Erythema is more likely to be present if, as can often happen, the vesicles spread up the sides of the fingers, to occupy the dorsal aspects of the fingers and hands. If the nail beds are affected repeatedly, a characteristic irregular transverse ridging, discoloration and pitting of the nails will also be evident.

Once the vesicles have reached their height, there are two possible outcomes. They may grow tense and rupture, in which case there is discharge of fluid, erosion and eventually the formation of yellow and white, often blood tinged crusts. This situation is more often associated with infection and the formation of pustules, in which case lymphangitis and lymphadenopathy may complicate the picture. Alternatively and more commonly the vesicles become dry, shrink and are reabsorbed without a break in the skin.

Whatever the outcome of the vesicular stage, which typically lasts 7-12 days, it is superseded by dry, scaling or fissured skin. The itching is characteristically replaced by soreness and pain. Once the "attack” has reached the end of its cycle, it is either replaced by another eruption, or the lesions will subside, and the skin return to normal.

The cyclic nature of this condition is sometimes a striking feature, with regular eruptions occurring at an almost predictable rate; the vesicular phase being followed closely by the dry, desquamating phase in wave-like oscillations. In other cases the two phases intertwine, vesicles are superimposed on dry, scaly skin, so that there is no clear-cut pattern. In a minority, when reoccurring attacks have continued for years, the vesicular phase disappears for the most part, and is replaced by chronic dry, scaly, lichenified eczema, with a greater or lesser degree of erythema, and fissures of the palms and finger flexures. This form is also often accompanied by eczematous changes of the dorsal aspect of the hands or feet

A remarkable attribute of this disorder is the excessive sweating (hyperhidrosis) that often occurs on the palms, fingers, soles and toes of sufferers. Over the years many clinicians postulated that the vesicles form as a consequence of the sweat being trapped under the skin. This has now been shown not to be the case, although it is interesting to note in regard to the excessive sweating that the distribution of a typical eruption of pompholyx eczema significantly corresponds to the distribution of the emotionally activated sweat glands of the palms and soles. At least one study1 has shown that when patients were trained to control excessive sweating by biofeedback, there was improvement in their condition. This confirms the common finding in practice, of attacks being triggered by emotionally stressful situations.

Pompholyx eczema can lead to significant morbidity. Due to denudation of the fingers and palms, regular eruptions on the hands can make the simplest tasks such as cutting vegetables, peeling fruit or handling paper a major problem, whereas pronounced eruptions on the feet can lead to incapacity and even inability to walk.

Diagnosis

Pompholyx eczema is a straightforward condition to diagnose, and tends not to be mimicked by other conditions. However care should be taken not to confuse it with the following common conditions:

Fungal infection. Fungal infection is much more common on the feet than on the hands. In the early stages it is almost always asymmetrical in its distribution (affecting mostly the spaces between the 3rd and 4th and the 4th and 5th toes, with a circumscribed area of vesiculation and scaling. A scraping of skin examined under the microscope will easily confirm the presence of mycelium. Although very uncommon, it is worth mentioning here the so-called "Id reaction”. Fungal infection elsewhere on the body, most commonly on the feet, may provoke an eruption of pompholyx on the hands. Confirmation of this link depends on disappearance of the eczema when the fungal infection is eradicated. In such instances successful treatment will only require resolution of the fungal infection.

Contact dermatitis. Contact dermatitis (allergic or irritant) may also present with asymmetrical lesions, although it tends to affect the dorsae of the hands and feet and the sides of the fingers or toes where the epidermis is thinner and therefore more susceptible to irritants or allergens than the thicker epidermis of the palms and soles.

Pustular psoriasis. Yellow pustules on an erythematous background is the common presentation of this stubborn disease. The pustules typically resolve within 5-8 days, leaving characteristic brown patches and desquamation. Although clear vesicles may initially appear, they tend to rapidly become cloudy with purulent fluid. Itching can also occur with pustular psoriasis, but in contrast to pompholyx eczema this is not so common nor as severe, with soreness and pain being a much more frequent complaint. Occasionally with infected pompholyx eczema, pustules may emerge that superficially mimic the pustules of this type of psoriasis, however a correct diagnosis should be possible if a clear history is taken and it is noted that the pustules do not resolve into brown patches.

Page Created:14/8/03