As autumn arrives in the UK, we see a change in skin problems from sun-related conditions to the effects of cooler and colder weather. Eczema is common with many sub-types but the autumn and winter months can exacerbate some forms of the disease. Asteatotic eczema [AE] (also known as xerotic eczema, eczema craquele or winter itch) is a very common sub-type that will be visually familiar to podiatrists. As the temperature and humidity drop and the central heating goes on, the skin becomes drier leading to the development of a discrete dry, scaly patch or two on the legs, arms and sometimes on the dorsum of the foot resembling the bed of a dried lake. As the lesion enlarges it may take on a more nummular or discoid appearance with more redness, weeping or crusting.
Asteatotic Eczema on the dorsum of the foot showing the "criss-cross" pattern
AE can be itchy but is often not. The elderly are most often affected by the condition. It is caused by the skin producing insufficient natural moisturising factors (NMF) and consequently drying out. The reasons for this are multifactorial but include:
Increasing age
Excessive bathing/showering and/or drying (all remove NMF’s from the skin)
Low humidity
Illness
Menopause
The side effects of medications
Hypothyroidism
Zinc deficiency
The affected skin is dry with a slight, fine scale. On the legs, it can take on a “crazy paving” appearance whilst on the dorsum of the foot it takes on a more linear criss-cross pattern on the skin. The condition may be mistaken for tinea but fungal infection has more discrete lesions typically with a raised, erythemic edge.
Is it worth treating? Well, an eczematous lesion represents a localised area of skin failure. That is the skin is unable to perform its normal barrier functions. Consequently, exposure to noxious agents such as chemicals can lead to a more rapid skin penetration which may lead to sensitization and the development of allergic dermatitis. Moreover, eczema can potentially enlarge and spread further.
Eczema affecting the foot and ankle
Management
For most, it is straightforward. Modification of the bathing and drying regime by reducing the frequency, duration and temperature (if too hot) can be beneficial and preserve more NMF in the skin. When washing or showering, gels and soaps should be avoided. The legs should be thoroughly rinsed to remove any residue of products that may have run down the legs during showering. Soap substitutes should be encouraged – these are available from the pharmacy but do warn patients they can make the bath or shower more slippery when using them.
Drying should be encouraged by dabbing and not rubbing as this can irritate the skin further. Avoiding exposure of the skin to sudden changes in temperature can also be helpful. Woollen socks should be avoided as they tend to irritant the affected skin. Emollients are the mainstay of treatment. Urea-based emollient products are particularly useful. A recent study in adults with asteatotic eczema showed how four-week twice-daily application at reducing symptoms including itching and scale [1]. For those patients with more stubborn lesions, the addition of mild corticosteroid cream can be helpful.
Reference
1. Tsunemi Y, Nakahigashi H: Clinical study on the effects of the applied volume of moisturizer in patients with asteatosis. The Journal of Dermatology 2021