Dry Skin (Xerosis, Xeroderma, Asteatosis)

Introduction

• Definition: Dry skin refers to skin that feels dry to the touch due to a lack of moisture in the outer horny cell layer (stratum corneum), leading to cracks in the skin surface.

Demographics

• Affects both males and females of all ages.
• Some racial variability in water and lipid content of the skin.
• Nearly everyone over 60 years of age has dry skin.
• Common in people with atopic dermatitis.

Causes

• Early Childhood: May indicate ichthyosis.
• Later Onset: Postmenopausal females, hypothyroidism, chronic renal disease, malnutrition, weight loss, subclinical dermatitis, certain medications (oral retinoids, diuretics, epidermal growth factor receptor inhibitors).
• Environmental Factors: Low humidity, excessive air conditioning, direct heat, excessive bathing, contact with soap, detergents, solvents, inappropriate topical agents, frictional irritation.

Clinical Features

• Appearance: Dull surface, rough, scaly, less pliable, cracked.
• Location: Commonly involves shins.
• Severe Cases: Inflammation and fissuring.
• Associated Conditions: Specific types of ichthyosis.

Complications

• Eczema/Dermatitis: Atopic eczema, eczema craquelé, nummular dermatitis/discoid eczema.
• Others: Flaky skin, pruritus, skin infections, overheating, food allergies, contact allergies.

Diagnosis

• Children: Family history, age of onset, appearance at birth, distribution of dry skin, associated features (eczema, abnormal nails, hair, dentition, sight, hearing).
• Adults: Medical history, medications, topical preparations, bathing habits, environmental factors.
• Additional Tests: Skin biopsy and other tests for specific types of ichthyosis.

Treatment

• Moisturizers/Emollients: Applied liberally and often to reduce itch, improve barrier function, prevent irritant entry, and reduce transepidermal water loss.
• Factors: Severity, tolerance, preference, cost, and availability.
• Additional Treatments: Topical steroids for itch or dermatitis, topical calcineurin inhibitors if steroids are unsuitable.

Prevention

• Aggravating Factors: Eliminate them.
• Bathing: Reduce frequency, use lukewarm water, avoid hot water.
• Hydration: Drink plenty of water.
• Humidifier: Use in winter, air conditioner in summer.
• Soap Substitutes: Use synthetic detergent cleansers, water-miscible emollients, bath oils, anti-pruritic tar oil, colloidal oatmeal.
• Emollient Application: Apply liberally and often, especially after bathing and when itchy.

Outlook

• Tendency to dry skin may persist lifelong or improve with control of contributing factors.