User:Hdk23ph/Xeroderma

Xeroderma, xerosis or xerosis cutis, or simply dry skin, is a skin condition characterized by excessively dry skin. The medical term xeroderma is derived from the Greek words meaning dry skin. Xeroderma occurs most commonly on the scalp, lower legs, arms, hands, knuckles, the sides of the abdomen, and thighs.

Incidence of xeroderma increases with age. Environmental conditions, occupation, medications, medical conditions, and malnutrition can also increase the risk of xeroderma. It can be prevented with the use of gentle cleansers, specific bathing habits and moisturizer use. In most cases, dry skin can safely be treated with emollients. Anti-inflammatory agents can also be used in severe cases of xeroderma.

Signs and symptoms
Xeroderma is a skin condition in which skin is extremely dry and rough. It is often accompanied by itching of the skin. Frequent and rigrous scratching of the skin can expose it to secondary infections. Sometimes you can also see scaling, flaking or peeling of the outer layer of the skin.

Worse cases of xeroderma or dry skin can progress to cracks, fissures or swelling of the skin. Cracks and fissures can eventually lead to bleeding if deep enough. Individuals might experience tightening of the skin particularly after showering or bathing. Xeroderma is a most common clinical sign of many dermatologic conditions such as atopic dermatitis (eczema), psoriasis and ichthyosis.

Causes
Xeroderma is a very common condition. Environmental exposures, occupation, aging, medical conditions and malnutrition are some of the factors that contribute to its occurrence. It happens more often in the winter and in the areas of dry climates. During winters cold air outside creates a low humidity atmosphere which causes the skin to lose moisture. Humidity levels of less than 10% are associated with xeroderma. Occupations that involve frequent hand washing to prevent cross contamination are at increased risk of xeroderma incidences. Health care professions such as nursing, dentistry and food industries are some of the examples. Using harsh soaps can further enhance this risk.

As a person ages, the structural and functional changes in the skin makes the skin more vulnerable to xeroderma. The integrity of the skin is protected by the stratum corneum, which is the superficial layer of epidermis. Stratum corneum (SC) holds the moisture in the skin and prevents the skin from drying. It does so by the action of intercellular lipids and natural moisturizing factors (NMFs). Intercellular lipids regulate loss of water from SC by blocking water diffusion across the layer. On the other hand, NMFs ensure absorption and binding of water in the SC. Hence, both intercellular lipids and NMFs along with many other cofactors such as pH of the skin, proteins, various proteases, keratinocytes, sebaceous glands etc are essential for maintaining the hydration of the skin. However, with advancing age these components tend to weaken increasing the risk of xeroderma. Lipid content of the skin decreases with age. Elderly people often have chronic medical conditions and medication regimen that can also deteriorate the skin barriers. For example comorbidities such as Alzheimer's disease, ichthyosis, psoriasis, hypothyroidism, diabetes, chronic renal failure, liver disease, malnutrition and psychological stress are associated with decreased SC water content and increased incidence of xeroderma.

Medications such as diuretics, calcium channel blocker, antihistamines, statins and chemotherapy agents can also impair skin hydration. In elderly people xeroderma can rapidly progress to dry skin related pruritus. Hence, it is important to provide initial therapy to treat xeroderma in this population. Hormones also alter the physiological properties of the skin. Women are more prone to experience xeroderma than men with advancing age. Reduced level of progesterone and estrogen after menopause are associated with decreased sebum content and SC hydration. Photoaging can also increase the risk of xeroderma regardless of age. Substantial exposure to UV radiation especially UVA and UVB can cause lipid modification and degradation that can impair skin integrity. Generally skin in malnutrition is more prone to xeroderma and pruritis. A low protein diet is associated with thinning of epidermis and decreased SC hydration. Deficiency in vitamin A, D and zinc can cause atopic dermatitis which is accompanied by xeroderma.

Prevention
Xeroderma can be prevented with self measure care. Using soapless cleansers instead of harsh perfumed soaps causes less irritation to the skin. Frequent daily cleansing with harsh soaps and long showers can deprive moisture out of the skin. Short five minute bath once daily are preferred over showers to ensure skin hydration. Emusifying oils can be used in bathing water to provide hydration to the skin. Temperature of the bathing water must also be tepid, as extreme hot water can wash away further moisture from the skin. After bathing, gentle pat dry with towel is recommended rather than excessive rubbing.

Applying a non-perfumed moisturizer to a damp skin can add hydration to the skin. Some of the examples of non-perfumed moisturizers include Aveeno moisture cream, cetaphil and neutrogena. Moisturizer are available in cream, lotion and ointment forms. Lotions are ideal for hairy areas and areas of mild dryness. Ointments are the most occlusive in nature, and hence are preferred in severe cases of xeroderma. Ointments ensure SC hydration by blocking epidermal water loss. Alcohol containing products and other senstizing ingredients such as lanolin, aloe vera, propylene glycol should be strictly avoided as they can further aggravate dry skin. Humidity also plays an integral role in the prevalence of xeroderma. In winters, indoor humidity level between 45% to 60% is recommended to ensure SC hydration. Since malnutrition can contribute to xeroderma, a well balanced diet containing essential nutrients such as proteins, vitamins and minerals, and adequate water intake can ensure hydrated skin and overall wellbeing.

Treatment
Traditionally an outside in approach was used to treat xeroderma. In this approach non-physiological lipids such as mineral or vegetable oil were applied to the skin to restore lipid composition and functioning of SC. However, over time it was found that this approach is not ideal as these lipids were not able to cross the skin barrier and reach SC. Hence, current inside-out approach has replaced the traditional therapy. Inside-out approach focuses on providing easily permeable preparations to the skin that can stimulate epidermal differentiation in the SC. This will eventually restore the intercellular lipid content of the SC and its function to keep skin hydrated. These preparations are called emollients.

Emollients contain five essential components which includes humectants, non-physiological lipids, physiological lipids, antipyretics and epidermal differentiation stimulating agents. Humectants are hygroscopic substances that enhance water holding capacity of the SC, a function primarily of NMFs. The ideal humectant should have a molecular weight of 200-300Da so that it can cross skin barrier and reach its site of action in SC. Urea and glycerol are the two physiological humectant commonly used in emollients. Non-physiological lipids are the lipids that were used in traditional therapies. These lipids essential work at the skin surface by making an occlusive layer. They do not have a role in stimulating differentiation of SC lipid composition. Vegetable and mineral oil are the commonly used non-physiological lipids. Ceramides, cholesterol and fatty acids are the physiological lipids that are naturally present in the SC. Addition of physiological lipids in emollients is preferred over non-physiological lipids, as physiological lipids are able to penetrate into SC and can restore the lipid matrix composition of SC. Xeroderma can induce itching of the skin. Hence, antipyretics are added to the emollients to prevent physical damage to the skin from scratching and provide comfort to the patient. Glycine is a commonly used antipyretic agent in emollients. Lastly, epidermal differentiation agent such as dexpenthanol can be added to the emollient to enhance cell proliferation, lipid and protein synthesis.

Emollient comes in different formulations such as lotion, cream and ointments. An individualized emollient therapy can be prescribed based on what are patient's needs in terms of formulation type depending on the severity and location of xeroderma, as well as needs for adjutants such as antipyretic agents. In cases where severe swelling or inflammation is present, topical corticosteroids or calcineurin inhibitors can be used.