8.3 Dry Skin

Dry skin is one of the most common dermatological diagnoses and a symptom present in many dermatological and non-dermatological diseases (prevalence ranging from 35% to 85%). A study in a population of 48,600 employees the average prevalence was 29%, ranging from 17% in the 2nd decade of life to 39% in the seventh. Most people worldwide will experience dry skin at some point in their lives.

There is no gender predilection. Prevalence increases with age. Dry skin is one of the most prevalent skin conditions in the older adult population worldwide, affecting more than 50% of individuals aged over 65 years.

It is a frequent symptom in dermatoses characterized by skin barrier dysfunction (atopic dermatitis, psoriasis, ichthyoses, aged skin with dermatoporosis). It is commonly seen in individuals with underlying diseases (i.e., diabetes mellitus, renal failure, hypothyroidism, paraneoplastic, etc.) or who are taking medications reducing the lipid precursors or acting directly in the lipid composition of the skin.

Skin presenting a decreased quantity and/ or quality of lipids and/or hydrophilic substances (natural moisturizing factor) with increase of water loss, clinically manifested as a scaly, rough, cracked, and fissured skin surface often accompanied by pruritus. An ichthyosis-like pattern may develop.

Dry skin may be either a diagnosis or a clinical symptom present in several cutaneous and non-cutaneous disorders (disease-related dry skin). One differentiates between generalized and localized dry skin. A distinction is made between generalized and localized dry skin.

The onset of dry skin is thought to be mediated by genetics, environmental factors, ageing and other factors such as ethnicity. A so-called physiologic type of dry skin is to be seen in childhood with age related reduced function of sebaceous glands lipids and in the very elderly with atrophy of the skin (epidermis, dermis) and loss of function of sebaceous glands.

There are two main elements important for the maintenance of the epidermal stratum corneum humidity: intercellular lipids, which form the main barrier against diffusion of water across the stratum corneum, and a so-called natural moisturizing factor (NMF / formed in the Malphigian layer), which has a key role in the absorption of water in the stratum corneum. Filaggrin is a key player and genetically disturbed content and function leads to impaired skin barrier in particular in atopic dermatitis. The enzymatic proteolytic degradation of filaggrin leads to the natural moisturizing factor (NMF). An intercellular lipidic cement like composition of substances is produced by the keratinocytes and stored in keratinosomes of the corneal layer. These are ceramides, essential fatty acids and cholesterol. To keep the skin intact and supple, a water content of 10-15% is required.

Internal causes

In particular, during ageing of the skin and for example in atopic dermatitis dry skin the ceramide levels in the upper epidermis are reduced and ceramidase activity is increased, which lead to reduced functionality of the lamellar structure. A reduction of intercellular lipids in the stratum corneum and an altered ratio of fatty acids esterified to ceramide, along with persistence of corneodesmosomes, premature expression of involucrin and formation of the cornified envelope results in corneocyte retention and marked impairment of barrier recovery. However, in aged skin ceramides 1-6 synthesis is reduced, unlike in AD skin. In AD skin the sebaceous lipids are not reduced in dry skin areas, but in aged skin. Structural changes occur in parallel with a significant increase in pH values and stratum corneum hydration decreases with increasing dryness and skin roughness. Disturbed function of profilaggrin/filaggrin leads to reduced function of the NMF. Reduced activity of the sebaceous glands after menopause and andropause is an additional factor of loss of function for lipidization of the skin surface. Epidermal atrophy (senile) or hyperplasia (ichthyosis types, psoriasis, lichenification in chronic eczema), both coexist with dry skin. Certain foods and drinks such as sugar, salty food, refined carbs, and alcohol can pull moisture from the body resulting in dry skin.

Multifactorial aetiology:

External Causes

Intense skin cleansing/overwashing: Taking frequent, long, hot showers, hot bathing, using harsh, alkaline soaps, cultural washings.

Environmental factors: cold weather, low humidity, dry indoor heat, intense sunlight exposure. Irritant yarns on clothing.

Occupational factors: “Wet work”, contact with irritant agents (i.e., chemicals used in hair dressing or housekeeping, soaps, surfactants).

Endogenous Causes

• ageing

• menopause

• andropause

Skin diseases

Inflammatory skin disorders: atopic dermatitis, allergic contact dermatitis, irritant contact dermatitis, dyshidrotic eczema, asteatotic eczema (“eczema craquelé”), nummular eczema, seborrheic dermatitis, psoriasis, etc.

Infectious skin disorders (in the chronic phase): scabies, bacterial, or fungal infections.

Genodermatoses: Ichthyoses, xeroderma pigmentosum.

Neoplasms: Cutaneous T-cell lymphoma.

Internal/systemic diseases

Endocrine or metabolic: diabetes mellitus, hypothyroidism, hyperthyroidism, primary biliary cholangitis, cholestasis, hyperparathyroidism, renal failure and hemodialysis.

Inflammatory: Crohn’s disease, ulcerative colitis.

Infections: human immunodeficiency virus (HIV), hepatitis B or C virus.

Hormonal: pregnancy, menopause, hyperthyreosis.

Hematologic: myeloproliferative disorders, multiple myeloma, Hodgkin’s and Non-Hodgkin’s lymphoma, GVHD,

Paraneoplastic.

Neurologic: Autonomic neuropathy.

Psychiatric diseases

Obsessive-compulsive disorders: excessive skin washing.

Eating disorders: anorexia with nutrition deficiencies.

Addictions: alcohol or drug abuse, nicotine excess.

Dietary

Dehydration: excess perspiration, insufficient water intake.

Malnutrition: Marasmus, vitamin A or vitamin D deficiency, zinc, potassium or iron deficiency.

Medication-related

Drugs: Diuretics, beta-blockers, contraceptives, retinoids, long-term use of topical steroids, lipid- lowering agents (statins),

Radiation therapy, artificial tanning etc.

Dry skin is characterized by a scaly, rough, cracked, and fissured surface. Skin dullness with decreased elasticity, texture coarsening and wrinkling. Often associated with pruritus, that may lead to excoriations and haemorrhage.

Occasionally, erythema may be present. Rubbing and scratching of the skin can lead to eczematous changes with a reticulate, cracked, or crazy-paving appearance (“eczema craquelé”). Lichenification may occur.

Signs and symptoms of dry skin depend on age, health, humidity, and other environmental factors.

Dry skin can develop acutely or be a chronic condition of varying intensity (mild, moderate or severe dry skin).

Can be classified as:

1. Constitutional dry skin or xerosis cutis triggered by exogenous factors

2. Dermatoses that present with primary skin lesions such as atopic dermatitis, psoriasis, irritant contact dermatitis, or the various types of ichthyosis.

3. Dry skin associated with systemic diseases (e.g., diabetes, renal and biliary disorders, HIV)

4. Drug-induced dry skin

Variable. Although dry skin is often experienced in the winter, in certain individuals may be a lifelong concern. Can be aggravated by environmental factors such as frequent washing, use of harsh detergents and exposure to low-humidity (e.g. air-conditioned) environments. Development into an asteatotic eczema/eczema craqule and/or irritative eczema.

Clinical diagnosis with a thorough history and physical examination.

A careful and detailed clinical history including age, duration and localization of symptoms, timing, potential triggers, history of atopy, exposure to external factors, comorbidities (renal, thyroid disease, diabetes) and drugs (statins, retinoids, diuretics).

Prevention: Avoidance of possible trigger factors, such as aggressive skin washing and intensely hot water, soaps/detergents, extreme weather conditions, rough/tight clothing. Controllable environmental causes of dry skin should be corrected. Comorbidities should be appropriately treated. Excessive use of hot baths or showers should be discouraged. In childhood and adulthood, the frequency of bathing/showers should be reduced.

Therapy: Most cases can be managed conservatively with gentle cleansing and adequate moisturization with at least 4 % urea and/or lactic acid.

Use of mild cleansers: synthetic detergent cleansers or syndet cleansers. Avoid traditional alkaline soaps.

Skin moisturizers: Oil-based creams better than water-based lotions. Ointments are useful for preventing transepidermal water loss. They may include humectants (glycerin, urea 10%, ammonium lactate, hyaluronic acid, gelatin), occlusives (lanolin, paraffin, petrolatum, cholesterol, stearyl alcohol) and emollients (petrolatum, dimethicone). Application immediately after bathing/shower is recommended.

Choice of ingredients is based on a patient’s symptoms, such as scaling (e.g., urea), fissures/rhagades (e.g., urea or dexpanthenol), erythema (e.g., licochalcone A) and pruritus (e.g., polidocanol).

In cases with intense itch or associated dermatitis, oral antihistamines, topical corticosteroids or calcineurin inhibitors may be prescribed. In some cases, room humidifiers, especially during the winter months may be useful.

Dry skin is a benign symptom that can be resolved by avoiding triggers and incorporating adequate skincare. However, keep in mind that paraneoplastic or HIV related dry skin should be considered in refractory cases. Some cases may persist or recur for years. When associated with pruritus, it can significantly affect patients’ quality of life.